i have the onkyo m-504 and the m-506rs and ive owned a ton of amps before but i have to say,i use a dynaco pas 3 preamp,i totally rebuilt,new boards,tubes ,power supply,uses 4 12ax7 tubes,2 in the phono board,2 in the other board.this set up with 4 cerwin vega re-30 that i changed the tweeters out with aluminum horns,it gives me goose bumps.im running the m-504 in this set up.it has very low bass if needed,the highs are so clean and crisp,if ya take the time to rebuild a pas 2 or 3,you can use a solid state onkyo m504 and get the warm,crisp tube sound you want with out breaking the bank for a high end tube amp.ive seen ads (reveiws) on the m-504 sounding muddy,im telling ya,its not the amp,its your cheesy preamp or your amp is faulty.these amplifiers if taken care of will last for yrs.i bought these 2 amps used,350 bucks for the 504 and 250 for the 506rs.i gave my son the 506rs and he loves it.theres so much head room on these amps,half throttle and the shingles on the roof are flapping,joking you get the pic.if you can get one of these amps at or below 4 bills,get it,you will love it and they are nice to look at.165 rms wpc with 0.003 thd 120db s/n ratio.its 49.5 lbs but nice built amps are heavy.people complain of a amp being heavy,well i dont carry mine every time i use it so i dont care about the stupid details of weight.i had to put this review in because of a few bad ones i read and theres must be a bad one ,im betting its their preamp.put poop in,you get poop out.amps do that.

I purchased the Onkyo M504 approximately 20 years ago at a store called CRAZY EDDIE'S. I paid full retail $840.oo , which was a small fortune at the time for a college student.. I also got the preamp p-304 and the quartz tuner t-9090..total cost approximately $2000.00. I saved for this set up and i am proud to say i never looked back. I complimented my system with KLIPSCH bookshelf speakers and today i still own the set which is in "Mint", condition. I love my amp and the power it cranks out. The amp has never given me a problem and the sound it produces when i'm cranking the volume does not sound distorted or muzzled like other amps. I will cherish this amp forever. Its a classic

I can not say enough good things about this amp. Only thing that I wish is that it was an M-508....wihich is on its way....WOOOO HOOOO!!!!
Before I get started though, let me say that these amps are designed for musical performance. I would recommend them to anyone looking for a power source for their vinyl or cd's in the $1500-$2000 range. If you are looking for a home theater system, I would recommend looking for an amp that is bridgable (these are not).
I have dreampt of owning this amp (either one) since I was in highschool. Without giving away my age, lets just say that was decades ago.
These monster amps are absolutely BEUTIFUL!!! The clean lines and lack of flashy lights and over bearing lettering schemes combined with the flat black textured case, brushed aluminum front panel and wood side panels, make these amps a piece of art.
The meters are very large. However, I find that this does not take away from the prescense of these amps but actually ads to it!! They are analog instead of lighted bars or LED's. There sensitivity is right on the money.
The power of the 504 is rated at 165/channel into 8 ohms. I have mine being controlled by a P-304 and at half throttle, Diana Krall's angelic voice and dancing fingers on the ebony and ivory barely breaks the half way mark of 5 watts, but boy does it fill the room with sound. To those of you that are not knowledgable and think that you need 500 watts to hear everything, I will tell you that you are wrong. This amp is among the most efficient I have heard at low levels and every little detail comes out as if you were right there and she was singing in your living room.
I paid just over $400 USD for my M-504 off of eBay and just recently won the M-508 for just over $500 USD. Both a steal!!! If you have the opportunity to find either of these fabulous units, BUY IT!!!

Other components in this dedicated audio system:
Monster HTS 3600 MK II Power Conditioner
Onkyo Integra M-504 (soon to be the FABULOUS Grand Integra M-508) power amp
Onkyo Integra P-304 control amp
Onkyo CS5VL SACD/CD player
Onkyo T4500 tuner
Music Hall MMF 7.1 (INCREDIBLE) turntable
Bose 901 Series VI (with active equalizer)

I got this M504 off Ebay for $250.00 and I can tell you that it's the best sounding Amp I have ever heard! Pick one up if you come have a chance to buy one!

Clean, neutral, and detailed power output. Good looks. Good Sound staging.

heavy and big.

I got this amplifier with matching preamplifier P-304 from a well funded foreign student who finished his Ph.D. program and went back to his country of origin. I consider myself as a music aficionado, not a snobby audiophile and I listen to all kinds of music depends on my mood. I have been using 10 year old Yamaha integrated amplifier which sounded natural yet somewhat lacked detail and sounded overly warm. My speakers are PSB 6T which are relatively good full range speakers and my listening/hobby room is medium sized with high ceilings.
After I got the M-504, I was surprised how heavy it was and I could see two massive transformers through the top vent slits. I was mesmerized by the beauty of the amplifier. The lighted dual meters looked really charming and professional.
After initial hook up, I played some rock music, mainly Led Zeppelin and Metallica stuff. They sounded very clean, holographic, and smoothly powerful. The base was tight and well controlled.
The voices were clean and natural and highs were crisp and sweet. My old Yamaha amp sounded lack luster and inferiorly detailed.
I listened to Nadja Salerno Sonnenberg's violin stuff. It sounded just sweet, detailed and airy vibration of strings just gave me terrible goose bumps. Full orchestra sounded just magnificent.
I do not know exact benefit of dual mono design, but engineers put two independent transformers to achieve something otherwise no cost efficient Japanese engineers put in two energy guzzling transformers. Segovia's Bach suite on guitar sounded more defined, detailed, and sweet. I could smell (?) sweet aroma of Segovia's Ramirez guitar through my PSB 6T.
Finally, I listened to liquid child's "diving faces", which is a heavy electric techno club piece. The bass output was awesome as my woofers moved back and forth and my house was shaking.
The M-504's dual meter danced harmoniously with PSB's woofers. The amp never lost its composure and remained neutral supplying clean, controllable power. M-504 played music quite well and it would be a killer amp for main home theater setups. I am glad and lucky to acquire this amplifier and it woke up my old PSB 6Ts as if they took some Viagra (?).

Similar Products Used:

Yamaha, Rotel, Marantz

+Dual Mono Design
+Value
+Watts for the Money
+Warm smooth sound

- Less refined than more expensive amplifiers

This is a quality amplifier for the money. For the $350 you can find this amplifier for on the used market, you'd be very hard pressed to find a similar amplifier value.

Dual mono design. 160w rms.

The sound itself isn't as refined as more expensive amplifiers. Thus, my 3 star overall rating.

However, this amplifier provides an excellent value. It would be an excellent amplification upgrade for someone with a mid-fi receiver or preamp.

The overall character of the sound is a bit on the warm side. Also, unlike more expensive monster amplifiers, this amplifier won't be comfortable with under a 4ohm load. Don't try.

Oh, and the wattmeters are neat.

Fantastic value.

Great looks good basic design.... tried and true dual mono constuction. Good with low impedance loads.

Input and binding posts could be better..but can't complain at this price point.

Without drifting away from the subject matter right from the start I will say that as with anything it is not how something is done but how well it is done. The M-504 is a shining example of that. All other factors being equal such as a quality pre-amp and speakers this power amp will deliver the goods as far as being free from irritating intermodulation distortion, has clean power for any respectable speaker,and used properly will give your ears many enjoyable hours of listening enjoyment. Fire and finesse is my rating on this wonderful piece of gear. Now before getting bashed I need to point out that I am looking at the total picture,price vs build vs performance. Is the M-504 perfect? NO far from it, but many others aren't either..and for a lot more money.2 transformer dual mono designs are far and few and to get 1 at this price point is a find. Sorry to say I wish Onkyo would have taken it a little further with better connections and a better lamp set, but the foundation for a truly good power is already there, so what's a few bulbs and a little upgrading? nothing considering what you get.

Clean Power and lots of it. Lovely from LED's , Bargain for the money .

Terrible binding posts, actually all the connections from the rear.

What can i say more to what's been said already. Seeing this unit in action about 5 yrs ago, decided this is the amp for my system. Though this is not for everyone. My system consists of:- Tjoeb 4000 Valve CD player Bottlehead Foreplay Preamp (plus Anticipation kit) Onkyo Integra M-504 Power Amp Mission 752 speakers (Rewired) Chris VenHaus Power & IC Silver Cables DH Labs Q10 Cable Initially installing the Onkyo M-504 there wasn't much difference between this and the Onkyo TX-777 Integrated HT Amp and was dissapointed. Then i decided to mod the Onkyo as far as i could ,the changes I made in order was. - Organized a replacement of a large number of audio caps (due to ageing).(7) - Installed an IEC Socket for a proper power cable (7) - Build a Chris Venhaus Power Cable (7) - Build the CVH Silver Interconnect Cable (7) - Replace the RCA's with the M-508 Gold RCA's (6) - Wire the Speaker cable directly to the speaker cable board (8) The numbers represent what value i place on the change 10 being the highest. What do I think now ! Now it sings ! It is quite a different beast to the original. Not still a lamborghini , but turned a BMW into a racehouse on steroids (legally). The soundstage is open and quite wide, dynamics completely changed, with a nice openness about the sound. I always ask would i do it all over again, the answer is absolutely it was worth all the effort. I still think without and changes it's a good power amp. I realize that the changes are not for everyone and is dependant on the system, but for me, I am very content .. at least for now !

Similar Products Used:

Onkyo HT amplifiers

Incredible power. Great design!!!

Speaker jacks

I read a large portion of these reviews and have 1 thing to say. Anyone who does not LOVE this amp is either tone deaf or has a poor set of speakers. Remember, it doesn't matter how good your system is if your speakers don't justify it. Having said that I see alot of unnecessary componants being used as well as inferior speakers. The way Onkyo was designed is best complimented by Klipch Speakers. Back when I bought my M504/P304's (85'), the reference line for Amp to Speaker combo's was Onkyo/Klipch. You can't beat this combo. These are the BEST AMPS for the money!!!

Similar Products Used:

Everything from Kenwood to Sumo (anyone remember Sumo Class A Amps)? If so your showing your age.

Power supply, gauges, musical tonal qualities.

A bit dated now with no optical inputs and poor connectors. Huge power drain upon startup, momentarily dims the lights in older homes with old wiring.

I bought this amp back in my college days in 1989. This amp has been used for my home listening on every imaginable speaker of mine and roommates. It has powered DJ events at my fraternity parties, presently powers my M&K LCR-35's, and it about to be installed in my $12000 home theater system in my new house. A great sounding amp with great versatility and reliability. Wish I would have bought 2-3 more. Getting a B&K Reference 5 channel for the Dolby 7.1, it will be interesting to hear the difference between the two. 15 years and going strong. A classic, beefy amp.