The ST-140's greatest strength is how warm and tube-like this MOSFET amp sounds. I find myself listening for many hours and the warm sound is not fatiguing whatsoever. Very musical, and very enjoyable on my dipole speakers. I've had my share of different power amplifiers, and I'm extremely happy that I rolled the dice on an old B&K ST-140 when it popped up for sale local on facebook marketplace. There was a local audiophile that was downsizing and selling off some of their gear. I paid $350 for the amp, they wouldn't budge on the price since it's in exceptional condition. I'd say it's worth even more after using it for several months because I would've easily paid $500 for this beautiful warm sound. This amplifier sounds better than the Adcom GFA-555 that I had and believe it or not it sounds warmer, and more musical than a Parasound A23 that I paid triple the price for. If you find one up for sale local like I did, buy it! I'm not looking forward to how much it will cost when I decide to upgrade from the ST-140.

This is really reaching for a weakness but I will say that I absolutely DO NOT like the speaker binding posts on the ST-140. They didn't want to accept standard bare 14ga OFC speaker wire. When I decided to use banana plugs like the previous owner was using, they feel like they're only plugging in half way and not making good contact. So unfortunately, the binding posts are not deep enough in my opinion to make what I feel is a good solid connection. The banana plugs stick half way out and are kind of wobbly. Yes, I've tried different length banana plugs, the B&K just has shallow posts. The right RCA input and the right speaker binding post is located on the far left of the amplifier while you're standing over top of it. Not a weakness, but I found this kind of bizarre. It's bizarre enough that someone used a label maker to mark the right channel. There's no speaker protection beyond the tube fuses located on the back of the amplifier. There's no soft start circuit, on is on and the rocker switch will make a bump noise on your speakers. The amplifier makes a Thumpy Thump noise on shutdown, similar to a needle drop on a record. I joined a B&K amplifier group on facebook specifically to ask about this noise because I was concerned. I was told from 30yr B&K amplifier users this noise is normal and it's nothing to worry about. I have a tendency to overreact about things apparently. Being the OCD person that I am, I purchased a quality speaker switch to use with the B&K. The switch is turned on last, and the switch is also turned off first. Now I'm able to avoid the rocker switch bump noise and the thumpy thump when the amp shuts down. I can also toggle to different speakers on the B&K for different types of music now.

This amp is Awesome, very musical and I'm using it with the pro-5 pre amp. I've used couple of other well known amps but I been driving them with my Vandee's excellent. Very detailed and awesome low end very tight and precise bass response. I like the fact they have the front handles and never overheats, as it has plenty of ventilation. The other thing I like about it is it's real raw power and can make older quality speakers sing goood.

Bass, accurate reproduction, powerful, soundstage

Will not work well with 4 ohm speakers, ask anyone with Maggie's. Not necessarily a weakness, but a limitation.

I bought this wonderful amp in 1992. I've run this amp in a variety of ways, stereo with B&K pre-amp, in HT driving the front channels with a Pioneer Elite receiver. Currently I use it with and Adcom Pre-amp in a music only stereo set-up, where it belongs. I've used Canton Karat 930's, and my current speakers, Energy Connoisseur C-3 with a Hsu subwoofer. The soundstage is fantastic. It's great with bass and a great amp to start with in high-end stereo. I have pretty eclectic taste in music, from Floyd to Coltrane to Latin, Classical, and 70's funk. It's dynamic enough to handle all of those well. I've had to replace a fuse just once in all of my years with this amp, and that was 10 years ago.

musical. very good soundstage. can bring out some of the passion in a recording.

power cords. mine came with cheap ones. i replaced them with shielded 14 ga. ones from volex @ allied electronics.

i live in canada. i purchased these amps (dedicated mono blocks) from the U.S. on ebay last fall, but didn't hook them up until recently. i have owned mono'd bryston 4B's, & 7B's before, but have downsized my system for practical and economic reasons (read: new baby !). i was using my old dynaco briefly before hooking these up. the 4B's always sounded 'gainy' to me. the 7B's not so, but still very powerful. these amplifiers are musical. subtle. i was wonderfully surprised.

i did separate them from one another (on the floor), and noticed an immediate improvement in every aspect.

i listen to older popular music. as i started to listen to these, i was soon back to my favorite CD, 'Famous Blue Raincoat' by jennifer warnes. this CD was, and still is, wonderful. as it played, i was drawn in to the songs, listening to four tracks, instead of just the one i had intended. i noted that my girlfriend had also been drawn in, as she stopped doing what she was, and joined me on the love seat.

jennifers' voice was pure, and instruments were in place in the soundstage. the soundstage itself was excellent in width,and depth. my girlfriend made comments about the songs now, even though she had heard them many times before. the bass was full, with less authority than the bryston's, and maybe better because of it ?

i next put on 'brothers in arms' by dire straits. 'your lastest trick' sounded very good, prompting me to bring out the album version. the record promptly outdid the CD. the soundstage had good depth, much deeper than the rear wall. again, everyone was placed well within the soundstage, and you could 'see' them move around.

i will say that the amps present a more refined, relaxed quality, to certain songs. they are very easy to listen to, with no fatigue.

other equipment:
esoteric cd player
counterpoint sa-7.1 pre amp
canare interconnects and speaker cable
magnepan mmg's
hsu research sub

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bryston

Natural, neutral, smooth, reliable and affordable!!! Tube like sound without the hassels or the expense, and there's a nice weight to bottom end as a bonus.

Does not have the "status" of the ultra expensive high end units, which are more about glitz and face plates than music anyway.

A peach, an absolute peach!!! I've owned this unit since new (1985), yep 20 years ago, with never a lick of trouble. It has driven, with astonishing musicality, Boston, Vienna, Quad 57 and 63, and Martin Logan loudspeakers. Smooooth baby smooooth. Yes I've owned more expensive amps but have always returned to the ST140. This is a VERY natural sounding amp, if there is such a thing. It just sounds right to these ears, never harsh or etched, not bloated or muddy, just right. I love this little gem!!!!

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Audio research, Quicksilver and VTL

Tubescent.

Addiction leads to more spending.

I bought mine in 1989! Haven't been using it lately because I'm into five channel sound. I'm using a receiver, and I miss my B&K's warm sound. That blooming bass! Someday I hope to get it back into the system with a multi-channel pre-amp, but for now it rests in dry storage in its original packing. Long live the ST-140!

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Nothing like this one.

Very smooth and sweet sounding. Lots of power. Outstanding high end, Great mids, Wide soundstage with improved power delivery.

Very small non-removable power cord which was replaced. Lighted power switch died.

I've had this amplifier for around 18 years or so, so it must be one of the first models. It didn't come with a removable power cord and the outputs are on either side of a center heat sink. It runs fairly hot, but this hasn't effected the reliability as it's been left on for most of the 18 years and still going strong. The only thing ever to go wrong was the lighted power switch, which I have replaced. One of only weaknesses IMHO is the power cord which was the size and weight of a typical table lamp. I understand later models had an IEC. I suspect that this is why it's transient response on the bass end was little weaker than it should be. In my renewed quest, of recent, to upgrade my system I thought I'd put bigger power cord on it and put on a custom 10 gauge homebuild cord. Wow, what a difference. The soundstage and overall bass response improved dramatically. Now it's not just a great amp, it's supurb and I think I'll be keeping it for a few more years. In fact I may buy a second one and have it converted to mono just to get a little more "oomph".

the smoothness and dramatic souns stage

a bit soft towards the bass

If you are looking for a amp that is smooth and musical and not going to put a hole in your pocket this the amp for you. At 105 wpc you have enough power for most speakers in mid. to small rooms. this amp can tame your speakers, make them bloom, and fill a room with great sound.............and all ways for sall!

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PRO5 preamp GAS ampzilla Denon 1082 Integra 6.1 Eagle 4

Soundstage, warmth, balance

Soft bootie. Can be pushed by lower impedence speakers. It can sound a little strained if you push your Maggies or other electrostatics hard. East does it!

I have owned the ST-140 on and off for about ten years now and never fully tire of its attributes. I does sound "Tubey". Not as much as some early 70's Marantz; but it does sound warm. I haven't heard any MOSFET stuff recently that sounds as pleasurable under $1000. I'm much more impressed with this guy than anything that ADCOM, Carver(ICK!) etc. It has a softer tuch but I find that refreshing given that I enjoy many British loudspeakers. My current speakers are Acoustic Energy Aegis 2's,CD player is a CREEK CD32.Budget but great sound. The speakers and amp dual up to throw a helluva soundstage with nice balance. And it is that balance that I believe sets the st-140 ions ahead of pricier competition. Until I can afford an ACURUS DIA-100, I'm hangin' with my 140. It's a honey. Find a used one in decent shape and you're in for a treat.

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ADCOM GFA 555, Denon AV receiver, NAD power envelope.

Simple build. Not much in the cabinet. Big caps, medium size torroid power supply, dual mono construction, removable IEC power cord, good connectors

None so far

This is a very decent amp for the price. It's not a Bryston, but it's a lot better than my previous Adcom GFA-555. Although rated at only 105 w/ch, it drives my speakers a lot better than my Adcom....much more definition and solid clear bass. I've read people say this is a good amp to tame overly bright speakers as it's somewhat subdued, but I think it's quite the opposite. Quite well defined and spacious. Well made case. If you can get for under $300 US it's a deal.

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Adcom GFA-555, Carver 1.0t