Since I now own 2 sets of 60 V. Maraschino King monoblocks for my 2 main systems and have also used a 48V STM, I thought I would comment on sonic differences.
Both systems are high resolution. One system drives Avalon Opus, a 4 way system that is a smaller version of the Eidolon, w/ Accuton and Eton drivers and some load complexity and lowish sensitivity, and the other uses a pair of 7" two-way stand mount LaHave Melas, an easier load. I use virtually identical front ends and cabling, both using TDSS modded Nuprime DAC 10H dac/preamps.
The STM uses one 48 V power supply, and the Kings are true mono with a pair of larger 60V PSs, and are much more powerful.
The net result of the switch was similar on both my systems, although more noticeable on the Avalons.
Right off the bat, I'd say that they sound very similar, as you might expect. Both have transparency focus, balance and smoothness in spades. Both can drive either pair of speakers with authority and are class leading, IMO.
The effect of moving from the STM to Kings on the frequencies above 200hz. or so is fairly subtle. There is a bit more "ease" and focus generally, with the STM being perhaps 90% of the Kings in that range.
Below 200 or so the overall focus, tightness, focus and clarity through the bass range is improved with the Kings, and the bottom end "slam" is sharper and more impactful. The Kings offer more clean dynamic slam (startling at times) than any amp I've had, and have rarely heard elsewhere, so the STM is up against one of the best in that dept. The improvement is clearly audible to me, and once again as expected the Avalons are most improved. In the lower ranges I'd give the STM 80-90% of the Kings, if those numbers make any sense, but still very satisfying on its own terms.
Given the mono Kings are much more than double the price , there's real value in the STM. Of course, the 60V King supply can be purchased and used with the STM as well, probably narrowing the differences.
I won't speak for anyone else, but if the $ is a big factor, the STM is one h*** of a bargain for the quality received.
For me, I feel fortunate that I own TWO amps that approach SOTA at a combined price less than the price of a single comparable quality high power audiophile amp.