@dkerr
same speakers used for both amps, st 100 and a21+ , 86db harbeth shl5+.
overall i liked the sound of the stereo100 better, more dynamic, more organic, ability to tube swap, i used amperex 12ax7 and rca 12au7.
i bought the a21+ thinking it would improve bass response. wrong.
i never replace a new component with one i sold off, throwing good money after bad.
the a21+ is an excellent solid state amp and it does sound very good and can play quite loud without fuss.
ps i also demoed the hegel h20 and did not care for the sound of the system, thin, overly transparent amost surgical with ker r11 towers.
the right preamp will meet your goals. important to note is that the rogue RH 5 sounds much more dynamic than the RP 5 (no balanced connections either). it even sounds better than the twice as expensinve RP 7 which i owned. I was very disappointed in the lack of dynamics in the RP 7.
another one to try is the Cary SLP 98. even with rca connections it is very dynamic. check cary direct for good prices.