I wouldn't go so far as to say you could use the Samson's with any preamp, but from my experience I had no issues using different preamps and I don't see why a Dodd Audio or Red Wine Isabella wouldn't work. In fact, if your digital source has enough output, try a passive preamp. Some of the best sound I got was using the D-225 with a passive TVC (the Samson's are highly sensitive at about .8V and have higher gain than most amps). Then again I'm probably part of a very small minority that is a big fan of passive preamps. TRL can help you with a passive preamp as well to match the Samson's.
As for comparison to other amps. Well I think the biggest difference is the Samson's have the ability to play with "balls" or finesse based on your listening tastes. I've cranked up mine with no distortion issues and listened at the lowest levels late night and not missed a note. Rock, complex classical recordings, solo cello, chamber music, whatever you through at it the Samson's will handle it. My VAC amps I use now can crank it out, but at low level I do sense minor loss of dynamics and bass linearity. My Cary amp used to peter out too easily and was very colored. TRL will be very transparent. It will power your speakers with ease and run cool and efficiently in the process.