How far have ss amps really come in the last twenty years?

Frustrating is right Dave..... Tried left/right cable swap and remained in the left...I even tried entirely different brand of cables...no luck. Moved the chairs/sofa to another room....same.

"mrdecibel" and "daveyf", I stupidly did. The Krell KSA-250 was part of a 5.1 HT set-up that doubled as a stereo system. I used the Krell for front L/R and two Pioneer Elite M91 amps for rear L/R and one for the center channel. Sure looked nice. But, the whole system was heating up my HT room dramatically in the summer (I lived near Houston at the time). So I replaced all three SS amps with a Krell TAS. Heating problem solved. But, it was obvious the Krell TAS was not in the same league as the KSA-250. Like I said, I have regretted the decision to sell the KSA-250 ever since. Probably my single most stupid HiFi decision in close on 50 years with this wonderful hobby! But then again, probably best not to talk about the Wharfedale E90 speakers.

The nice thing about the Krell TAS versus the KSA-250 is reliability. The KSA-250 runs so hot it is obvious a re-capping will be required at sometime or something will fail due to the extreme heat. Not so with the TAS, the Krell service department tell me this is an extremely reliable amp and very rarely needs repair. Ah well, peace of mind is worth something in this instance.

@stringreen   Wow, strange. I think that there could still be a room node that you are hearing. Do you have any acoustical damping in your room/system?

@mgattmch  That is one of the issues that I think has gotten significantly better with many ss amps over the years....far less heat production. Although, the Class D amps, which run cool, leave a lot to be desired IME. Personally, a heat engine for an amp, isn't going to be on my radar anymore. 

amp tech has stalled in terms of design, although in terms of innovation and advances on some themes, amp builds are being updated with fresh lines of thought on how best to get from input to output.

one example I recall from reading articles on various amp tech is a more limited, or sparse approach in the use of MOS FET devices. presently some makers have reduced the amount of these devices within amps choosing instead of using four, six, eight or mnore to using only a pair per ch in the amp output stage, yet choosing them a lot more carefully with matching them electronically a far higher priority..

otherwise we have to be in agreement that the evolution of the parts themselves has escalated performancewise, and greater attention to isolation and power sup builds has handed us at least SS hybrids, class A, and A/B amps which appear to perform on higher levels with at times fewer parts.

new BK amps from PS Audio for example use this less is more approach. I believe darTZeel was using just one pair of bi polar devices back in '04 or '05 rather than multiples of same as has been the case so very often with sand amps which opt for such device topologies.

although this minimalistic attitude has been ongoing for a while in some maker's amps, it is in fact, 'new' design techniques, so there's that.

more tube amps are now using cathode follower designs for continuous auto biasing rather than mandating owners to self bias each amp and as said, actively engaging a 'continuous' auto bias circuitry, ala vAC's IQ line of amps.

jolita Black Ice INTs partnered with FOSGATE designer to add in a sound enhancing tech to their 18 and 50wpc INT models currently available, or so I've read/heard.

its a tuff act to build an amp whose design is completely unknown, brand new, or not another take on a proven method.

its like reinventing the wheel.

one likely has to hang their hat on the 'less is more' tact, and greater attention to detail in the build's layout as something fresh in amp design, yet its not a totally new 'ground up' blueprint, just different.

i think until someone discovers the 'never before' ways and or means to transmit and develop signals, and does the same for output stage thinking, we will have to be satisfied with innovation and refinement, rather than be unsettled with the SOTA of amplifier philosophies seemingly remaining unchanged.

@string>
I suppose you have switched spkr cables from left to right to see if its not the spkr itself by now, and as such it is a disparaging and interesting concern at the same time.

Much luck to you.