question of soundstage

That would be like saying that an electric car outperforms a gasoline car or that a gasoline car outperforms an electric car. It’s all going to depend on the amps in question, the tubes, design, quality of the components, speaker placement, pairing etc...

There are way too many variables to make such a generalization!

If the amp is new maybe allow some time for the tubes to burn in.  When I bought my first tube amp, I was very disappointed and wanted to send it back right away.  It sounded like crap!  Laziness kept me from re boxing it and having to carry that heavy thing to the UPS store.   After a few months of use it suddenly "opened up" and sounded beautiful!  I am now glad I kept it.  I do prefer solid state though, unless it's a guitar amp.  Give it some time!

Which speakers are you using?  It may be a question of synergy.

. . . also not all tube amps (or tubes) are created equal.  As far as sound stage, I remember hearing a long time ago that monoblocks excelled at that.

Yep, lots of factors. 

The Sugden has greater channel separation compared to your tube amp.

Soundstage is a test you should use to evaluate an amp.  Cayin is not a high end tube amp and it isn't surprising for it to be outperformed.   My guess is that it is PC board based rather than point to point.  but that is speculation.

I'm not knowledgable on sugden, but they claim to be hand made in the UK for many years so that would point toward quality.

Jerry

I have Sugden Mono blocks, Before that I had the Sugden SPA-4 power amp. Same huge soundstage.I have a Sugden IA-4 in the basement,on my second system, same quality. Could be part of the Class A, or the synergy with the other components as others have stated.

I had a Krell FPB 600 hooked up to an ARC Ref 6 SE. I then upgraded my Krell to the ARC Ref 750s. Huge difference in sound stage. Soundstage definitely comes from the amp imo. 

different tubes have different characteristics even the same numbered ones. For example, the Sylvania Chrome Domes are not as side as the Linlai 6SN7 tubes in our preamp.  .Same goes for preamp vs amplifiers.

....and I've been subject to the delusion(s) of 'sound stage' (the perceived width x 'location(s) of performers/instruments') is more a function and/or 'synergy' 'twixt speaker types/room placement/room response...And the 'mixdown' of the applied musical selection...

Whereas, the electronics and the medium from which the selection is applied is (or ought to be) +/- a 'non-participant'...

I'm willing to accept and allow a %tage for LP's and 'physical media' of it's type....*s*

Devils' Advocate Hour.... ;)

Your equipment, cables, et all....ought NOT to add 'color' or 'warmth', which has already been and chided over as being terribly....subjective...*gasp!*L*

Oh....beg y'all's pardons....

You're referring to A amps....

As the woman was prone to mention after a rant or dozen....

"Never mind..."

I will preface my response by saying I am not an audio engineer and do not have experience with your equipment.  I will present my experience in the pursuit of sound stage as it relates to electronics.  Another preface is that the speakers, room, wiring and power  quality also apply.  From the perspective of electronics the factors that affect sound stage are channel separation/cross-talk, noise, detail retrieval, and macro/micro-dynamic retrieval.  Modern electronics have excellent channel separation.  I focus on detail retrieval and micro-dynamic retrieval and its impact on soundstage when evaluating new electronics.  I listen for how the equipment produces secondary harmonics and decay, leading edge reproduction, detail of the micro dynamics during decay, background noise, imaging and stage.  I have a few test tracks I use.  As an example, when I upgraded from my well maintained ‘97 vintage pre and power amp to my current integrated amp the improvements in these areas created a sound stage that was much improved and realistic.  So you cannot generalize that your tube amp will give a better sound stage than your solid state.  Your solid state may just be performing better than your tubes in the performance areas I mentioned. I believe my integrated amp performs as good if not better than most tube products I have auditioned, noting that I personally  am bias to the cooler clarity of well designed solid state vs tube equipment. 

Maybe try some tube rolling?  When I rolled from OEM tubes on my McIntosh C220 pre to Mullard reissues, my sound stage did widen a bit.

carlsbad2

You should not speculate and write negatively if you do not know about Cayins.

My Cayin A88T was deigned in Germany, built in China: hand built, point to point. Beautiful workmanship inside and out.

This extremely positive review is why I bought my Cayin A88T which sounds terrific.

https://6moons.com/audioreviews/cayin/a88t.html

excerpt

"The Cayin 88T is the first integrated amp I’ve ever had in my system that sounds so good, I have absolutely no desire to go back to the big mono block amps and the preamp. In fact, in many ways, the Cayin sounds better!"

"No, I didn’t decide to start this review with my summation. That wasn’t me talking. That’s a famous American manufacturer speaking".

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The more powerful A100T is also a terrific tube amp, 8 power tubes, individual bias pots and meter. Subsequent mark 2 and 3; and other models like the A100T have external bias adjusters and meters

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What tubes are in an amp is part of the different sound between amps.

Mine came with 6550 power tubes, I changed to KT88’s. It sounded great with the 6550’s, I prefer the KT88’s.

Bias: when switching tubes, I had the bias adjusted by Steve at VAS who used to be the distributor of Cayin USA. (my mark 1 has needed 16 ohm taps, bias is internal, no meter)

I blew a 6sn7 (put in 6sl7 socket), bought a matched pair, they sounded awful. Brent Jesse let me return/try a different brand, they sound as hood as the originals.

Thus, I would wonder what tubes are in OP’s very high quality Cayin.

I guess I should try some different preamp tubes. The speakers that I am using are the Tekton lore reference.

It’s not just Power Tubes.

My 6sl7’s made a big difference. (your A100t uses 1 6sn7 and 4 12AU's)

Originals: Labeled Cayin Brand, unknown maker, sounded great.

blew one (put in wrong socket), I wanted a matched pair of 6sl7’s that had a different appearance so I could not put one in the wrong socket.

Chose 6sl7WGT brownbase, chrome top, military matched pair.($80. each in 2020).

Nooooo. Wrote Brent Jesse, he had me break them in (amp on for 60 hrs, no signal needed), broke in for 3 days, still a no go.

Returned, full refund except shipping cost.

Tried 6sl7gt, General Electric, side getter, cylindrical plates ($40. each in 2020). They sound wonderful, as good as the original Cayin branded ones.

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Power Tubes

My amp came with 6550 Gold Aero, they sounded great. I have a set of 6550 EH Electro Harmonix, matched when new, but used,

I wanted to try new matched KT88’s, went for KT88’s Blue JJ Electronic, I prefer them.