How Do Amps Affect Soundstage?

I highly recommend to anyone in this hobby that they commit part of their upgrade budget and go to an audio show (I've been to AXPONA, Florida, and Pacific Audio Fest). You will come away with many of your preconceptions broken or severely damaged. There are rooms with solid state amplification that have extraordinary imaging and rooms with tubes that have mediocre imaging. And vice-versa.

I'm a geezer who has subscribed to Stereophile and TAS for 40 some odd years and I have never seen the experts answer the OP's question. There are lots of theories, mainly from amp and speaker designers, who tout their unique assemblage of parts and circuit design. They each say that they know the secret of superior imaging but if any single approach was better it would have been largely adopted by the rest of the industry.

I have experienced what the OP has observed, except that in my case it was the difference between two SS amps. I'm driving Thiel CS6 speakers (86db with a brutal impedance curve) with a Krell KSA 300S amp. I took the amp in to get it recapped and I tried hooking up my Onkyo AV receiver up to my speakers for the interim. When I listened to the first cut I literally laughed out loud. Compared to my Krell the sound was like an AM radio. I realize that this is an extreme example but anyone who thinks all amplifiers sound the same hasn't heard a comparison like this.

I believe that imaging and soundstage are primarily impacted by the design and performance of the speakers,  their positioning within the room and relative to lhe listener, and the room acoustics. The contribution from the amplifier falls far down the list compared to these factors. As @othercrazycanuck  mentions, tube amps are more prone to variations in frequency response and higher distortion, which are more likely than SS amps to impact imaging and soundstage. I tend towards the school of trying to recreate the intent of the musicians and recording/mastering engineer, which suggests minimizing additions to the sound. There are as many opinions on this as there are audiophiles, however, and beauty (and soundstage) is literally in the ear (and brain) of the beholder. So if it sounds good to you...enjoy.

Many good responses above.

Anytime an electrical signal passes through an electrical component or circuit or device, it will affect the music.  Be it distortion adding, soundstage, etc.

The discussion regarding the amp (Audio Research REF 6) paired with the Bryston is a great example.

Each device has a manufacturer's recommendation regarding input impendence, output impedance, sensitivity, etc.

If you try to match a pre-amp to a particular amp without paying attention to the manufacturer's technical recommendations, you are asking for trouble.

this is like trying to pair a particular amp to a particular speaker without paying attention to the specifications and requirements.

The REF 6 is one of the best pre-amps made.  I bet it doesn't match well technically to the Bryston amp and the specs probably indicate a mismatch.

Assuming that amps are amps, or pre-amps are pre-amps is the problem.

Of course different amp will affect soundstage.  They have totally different circuitry. Not an apples to apples comparison.

And by-the-way, don't fall for the old solid state vs tube argument.  There are some outstanding solid state amps out there that are just excellent.  Just as there are some outstanding tube amps out there.

I have heard some crappy tube amps and some crappy solid state amps also. Totally depends on the design, construction, circuitry, power supply, etc.  each is different.

It's funny.  I'm a member of a Mopar car club.  You know, Chrysler, Dodge, Plymouth.  I restore classic cars and currently have a restored 1970 in-violet, 340 four speed pistol grip Plymouth Barracuda ("Cuda").  Anyway,  People in my group always hype Mopar and with good reason and talk down about other cars.  I will step up and say loudly, you mean to tell me that if someone gave you the keys to a 1963 Split window corvette you wouldn't take it in a heartbeat?  They all laughed and said absolutely they would.

Tube or solid state.  What ever suits your needs and likes.

enjoy

@mossyrocks I humbly apologize. Now I am going to offend you again :-) but it is Parts Connexion. I don't know Chris. If you told him the same thing that you said above, that

I was finding I could not get the system to 'juice.

Than perhaps what he meant is that the volume control design of the Ref 6 is such that it is the chief cause of a high-ish (footnote here) output impedance. Footnote-the output impedance of the Ref 6 is not, in relative terms for a tube pre, all that high.

The Ref 6 in balanced mode has output impedance of 600 ohms and the recommended load of the amp for the Ref 6 is 20k ohms or higher. In balanced mode the load of your amp is 30k ohm so you don't have a mismatch on paper but it the margin is not great. This would primarily affect frequency response though it also affects maximum power transfer.

So again, yes, the match is not great. But the OP was asking about soundstaging and you SEEM to be talking about power transfer with "I was finding I could not get the system to 'juice.

In my admittedly limited experience, amplifier soundstaging is most affected by channel separation/crosstalk (hence, all else being equal mono blocks better than true dual mono better than stereo), sufficient real power (voltage and current), and competent design. For a moderate power and price amplifier, see Stereophile and Audio Science Review test results of the Benchmark AHB2.