I was a freshman in college in 1986 looking at receivers in a Crutchfield catalog when I came upon a full page devoted to the Peroton D940. It said "this is absolutely the best sounding reciever we sell". That was enough for me so I ordered it along with some EPI T/E 250's and an AR eb101 turn table. It always sounded awesome. I've gotten used to cleaning the pots and there is a service bulletin on how to fix the hum by replacing 4 small capacitors. Ive used it as my main power amp for TV, movies and music for 31 years. It literally has never been turned off except in rare occasions. I recently picked up an entire Klipsch Synergy II speaker system including ç2 center and 200 watt 10in subwoofer for $250 (shout out to Pro Sound in Elizabethton TN, that place is awesome!) The D940 is powering two F2 floorstanders withe two 6.5 in woofers in each with authority and has no problem keeping up with the 200w sub. I just picked up a used one on eBay for $85. The ginormous power supply is the key to this things power. I can't wait to see how two of these things sound bi-amped. Klipsch says the f2's are good for 100 watts each. We shall see. I don't think they meant Proton D940 watts.

Highly efficiant class "H" power amplifier. Very flexable with stereo components. Adaptable to virtually any impedance phono pickup. Low noise on FM. Very compact. Remarkable in general.

Switches and controls may need periodic cleaning especially if it is unused for awhile.

As a hobby I have seen and repaired many sets. It is very unique indeed. This one needed some cold solder points refreshed and the volume control needed replacement. I also did minor ajustments to the FM portion. So far I have had it about 2 years and it is a rather remarkable set. The low noise FM section is also unique in that it actually has lower noise floor than is expected. The "Power on Demand" is the highlight of this set in that it is a dual rail power supply class "H" setup. During normal (up to its rated 40wpc) the primary low voltage rails are used. When the peaks extend beyond that, the secondary higher voltage rails go into effect powering the second portion of the power amp. This really shines in a good digital version of the "1812 overture". In this it is the most potent 40wpc set that I have ever come across. It is adviseable to have speakers rated greater than 40wpc because the peaks can literally bottom out the woofers.

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Technics SA-800, Pioneer SX950, Sansui AU20000, Technics SU-V9, Technics SU-V85A, Marantz model 2270, Marantz model 4300, Pioneer SA-9900, Vector Research VR-7000, Pioneer SX-3800, 3700.

Dynamic headroom!!! All 6 dB of it. It is rated at 40 wpc continuous into 8 ohms, 20 - 20K Hz, both channels driven. Not so spectacular, huh? However, this Mighty Mouse receiver will deliver dynamic power peaks of 380 wpc into 2 ohms for 20 mS or less. That is incredible performance for any receiver or power amplifier, and it makes the music live. It also means that this magnificent little beast will drive virtually any speaker.

All of the controls are intuitive and easy to understand and use, and it is also built like a tank in many respects with the exception of the things I mention below in the Weaknesses section.

The preamp section is really very good, and the tuner is excellent.

None really, but I will mention a couple of little things. The switches and pots, although easy to use and very functional tend to get scratchy over time. Buy hey, everybody else's does too with few exceptions, and just working them good usually gets rid of the problem. Another is that the switch buttons are plastic and I they should have been made of metal.

The speaker connectors on the rear will not accept banana plugs although they look like the will. Proton felt that banana plugs could not effectively meet the current demands that might be placed on them in high power situations. They installed binding posts without the banana jacks for that reason.

These are minor things and in no way detract from the performance and the satisfaction of owning and using this little Mighty Mouse receiver.

Highly recommended! Every audiophile or audio enthusiast should have at least one, for backup if nothing else. It is that good.

I bought my first Proton D940 Stereo Receiver on eBay a couple of years ago, and I liked it so well I bought two more. I am an audiophile, or at least an audiophile wannabe since about 1985,.and I am no novice when it comes to audio gear. Actually, I buy audio gear and refurbish it for resale, and a lot of equipment has passed through my hands over the years, so I recognize good stuff when I see and hear it.

A little known fact is that this company, Proton, has made some very fine equipment for other well known audio companies. Remember the early NAD stuff. Well, guess what? Proton made much of it including those powerful little receivers they sold so many of back then, and which now still bring good prices on eBay.

If you can't get your hands on a D940 Receiver, try the D540 Integrated Amp instead. Of course, you will need a separate tuner for it. It has the same basic power capabilites that the D940 has.

Customer Service

No experience. My Proton D940 and D540 units are all vintage and have never needed repair other than minor stuff that I can do. The existing Proton website does not have any info or help on vintage equipment that I could find.

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Really too many to mention. Sansui G-971 Monster Receiver, Carver 900 Receiver, Harman Kardon 680i Receiver, Yamaha 777 Stereo Reciever, Yamaha 901 Stereo Receiver, plus many others.

As said above

It seems not very professional as its own sounds.
No remote control (but not very important because we just want its sound quality)

I have been so surprised as listening to the sounds that PROTON D940 created. It's too amazing, especially the bass and treble sounds. The bass seems deepl-lying, fully plump and powerful as I want (Even though only 40WPC, but may be because of Dynamic Power on Demand Technology). The treble sounds fine, pianissimo.

All I want to say that the PROTON D940 would ever making everybody surprised with the quality and power of its sounds.

If I can find out another PROTON D940 in its original quality (not any services or repairs applied yet), I would buy it event though I already had one) !

Let's try the PROTON D940 and you would believe my opinion !

Smooth, rich, clear sound. Great tuner. Lots of knobs. Powerful.

Switches get dirty and noisy and need frequent cleaning.

This was a great piece of equipment in it's day for a super low price. I bought mine in 1990 from Crutchfield on sale and my friend liked it so he bought one on 2nd markdowns for only $199 in 1991! I love the rich, strong sound this amp delivers. It's rated at 40w, but has plenty more on reserve for musical peaks. Sounds better than my Adcom GFA 545II 100w amp. Lots of real knobs for volume, bal, bass, treble. It also is bridgable, and has pre-out and amp-in connections. The only problem was the source and record selector switches get "scratchy" and need to be cleaned once a year, but other than that this was a very well built, heavy piece of equipment. The power supply in it is a beauty and is as big as a softball. After about 10 years of normal use, it started to hum. The hum got louder and I no longer use it, but I would buy one again if I found one in newer condition.

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Adcom GFA 545II.

Robust, solid with great sound

No remote, but my cardio-vascular fitness improves by getting my butt off the couch.

I bought the D940 new in 1986 (in Australia hence the price) and later added a Proton tape player and Proton CD player. I've used the D940 for 17 years and it hasn't missed a beat. A really great sound. Current speakers are Wharfedale 600 but most of my listening is through Sennheiser 500 headphones.

I'm just jaw dropped amazed that this thing sounds so good, given that it was manufactured over 15 years ago. Contemporary manufacturer's of receivers need to buy their own Proton D940 and learn a few "new and improved" tricks. Sounds a WHOLE lot bigger than it looks, not to mention refined output.

there's absolutely nothing to complain about! No This isn't Krell, but it's strikes me as world's away from any receiver made in the last 20 years that have been priced under $7-800.

won at ebay auction a few weeks ago. What a great find! New, in the box, with warrantee card, Proton D940! This receiver won AudioVideo's International Magazine's Hi-Fi Grand Prix Award in: . 1985! Powers just about every speaker I've got. It's particularly entertaining to run my Shahinian Acoustic speakers (42" tall, 81lbs each) with this tiny thing.

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Sony, NEC (A10II, killer 60wpc amp with 72amps reserves ... yes, 72amps), Levinson ... the rest were too long ago to warrant mentioning ... exceptin' that NEC A10II. I'll never, ever let go of that am

Authoritative, viscerally real sound. Plus, extremely flexible with many inputs/outputs, etc. Nice looking in a restrained, classy '80s way.

Buttons! Plus, I wish the tuner display could be turned off when listening to other sources.

I picked this up from eBay after reading all the great reviews here. All I can say is, "Thanks everyone," because they were right. This is the best sounding receiver I've ever heard. From the moment I turned it on I noticed a sense of authority and depth to its sound, a dynamic realism I'd been missing before. The Proton seems to reach out and grasp the notes with great strength and dexterity, and serve them up with impact. One of my first impressions was that a piano actually sounded like a piano - there was a a certain resonance and fade to notes that simply sounded authentic. The Proton does sound slightly warm but this does not translate to "muddy." It's clear and seems to have an extended treble that remains smooth throughout. It meets the rising and falling dynamics of music vigorously; when listening to classical, for example, if horns suddenly come in loudly it's felt with at least somewhat realistic impact...it's so visceral that it can be startling. Don't laugh, but this has brought to mind memories of hearing the band play during halftime at college football games, like I'm hearing real horns again through brisk autumn air. "Dynamic Power on Demand" is not just some marketing label; it actually describes what this unit provides. I can imagine that the amp is of somewhat better quality than the preamp section, but the only criticism I can mention is that I've noticed a slight noise through the speakers when adjusting the treble, which I don't often do. Maybe this could be cleared up - and it's very minor - with a shot of cleaner to the control. The switches, I agree, do seem a bit fragile especially when the sound and the general construction of the unit seem so robust, but so far everything's worked just fine. I handle them gently - it's worthwhile. As a basis for comparison, my last system included a Dynakit ST-70 amp, Adcom GFP-565 preamp, Music Hall MMF-5 turntable and Rogers LS3/5a speakers. Occasionally I'd hook up a friend's CD player. Before that I had an NAD 304 integrated amp with a 502 CD player and, well, a variety of speakers. At this point I'm thinking that the 304 was fairly pathetic in terms of the sound it produced (flabby), because I have another 502 connected to the Proton now and it sounds great. The Proton doesn't have the obviously "tubey" sound through the midrange that the Dynakit produced, but I'd have to say it's more authentic in the mids and creams the ST-70 in terms of dynamic range, clarity, and impact. I'd like to have heard it through the Rogers' but sold them beforehand; right now I have PSB Century 500s, painted and slightly modified - with an 8" mid/woofer - and they are really sweet with the Proton/NAD 502 combo. Highly musical, and listenable for hours without digitally-induced headaches or other irritation. If your wallet allows for big-buck separates you're probably not going to be interested in a receiver. I know I thought I'd never buy a receiver again. But for an audiophile on a budget, someone who may be shopping for a decent integrated amp from, for example, NAD or Rotel, I'd strongly recommend listening to the Proton first. Along with the sound quality you'll get a nice tuner thrown in - I have to admit I've really enjoyed listening to the local jazz/classical station out of Philly. The only caveat is that you'll have to be tolerant of owning used equipment, but I like to think of the D940 as something of a cherished minor classic. If it breaks, it will be repaired - I'll never sell, period!

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See above. Also, had a Yamaha receiver back in college days which really was absolute junk next to the Proton.

Warm sound, nicely defined bass. After 12 years of ownership I opened the receiver in order to fix the noisy input switch and I am amazed how well this receiver is built.

Input selector switch. Dust is it's biggest enemy.

I bought the Proton D940 Receiver about 12 years ago after I built Davis M4 speakers. Since then many friends were amazed how nice this set sounds. Nowadays receivers have much more electronic gigs. I love the plain design, wish I could buy this receiver new again! Though, a remote control would be nice. Funny detail, the input selector shows DAT instead of CD.

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None, until now I didn't find a receiver with the same character.

Amazing power. I''''ve hooked this up to big crappy fisher 15" speakers and it used to put out a lot of sound. The loudness button works great for low volumes. Heavy and very solid. Taking it home, I knew I bought a well-built receiver or a box of lead.

The switches suck. Not only did all of the dials give out, the power switch has broken on me twice. I used a power strip to turn it on/off for about ten years.

I saw some recents postings regarding this receiver and had to throw my two cents in. I bought the D940 new in about 1985 and have loved it ever since. I hauled it down to the Virgin Islands and back during an internship because I couldn''''t stand to be without it. About a year ago, after the third trip to the repair shop (to have the switches cleaned) it developed a hum and I decided it was time to replace it. I found the Harmon Kardon HK 3370 refurbished at a great price and put the Proton in storage in the garage. I was about to buy a small receiver to power some AR bathroom speakers and pulled out the D940 to give it another try. Well the hum is gone (I think it might have been the outlet afterall?) and I can''''t believe how great it sounds. I''''m tempted to pull the HK from my system and give this a try. Well, I can''''t live without the remote and sub out option, but if I can find a shelf to put this, I''''ll enjoy my showers more. Don''''t get me wrong, the HK may sound more refined and be more reliable, but I don''''t think I''''ll develop the same passion for it.

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