Current & voltage are essentially the difference between simulated pentode tubes (current) and solid state (voltage) amplifiers. This will make a difference in the warmth of sound in 2 channel mode and may be more audible when you:
1) are using a really good source (1/2 speed lp, 24 bit cd, original master recording)
2) are cranking the volume
3) are playing acoustic or unplugged recordings
4)have great speakers (accuracy not just sounds good - listen to each note and chord on each instrument for accuracy, not fullness. minor chords should sound a little schrill and cutting. Bass will sound more like a bass than powerful thumps
Although tubes distort at a higher level, they do it in a different and much nicer way than solid state. many musician s use tube amplifiers to increase the warmth of thier instruments. So if you want to hear it the way they recorded it, then this is likely a better setting especially for jazz of classical. remember, theater/movies are not a sonically great environment as the emphasis is on the midrange with instantaneous big bangs and booms; whereas, most music does not go from 70 db or less to 100db plus in an instant 1812 Overture and similar aside.
The fact is the circuit board for obtaining the best theater sound vs. the best musical audio sound would be and are designed differently. Thus, the purest will either have two systems or buy the one that provides the best in one area and deal with the other being substd. in comparison.
One of the few processors which comes close to doing both equally well (I said close, nothing more) in this price range is the little Lexicon MC-4. I love the Sunfire TGP and even the TGR, but Sunfire does not provide an upgradeable platform which means every few years when the latest in Dolby and THX arrives a replacement is required. The Lexicon is upgradeable and whether one has the MC4, MC8 or MC12 (a reliable Ferrari), they can simply download the latest and move forward with the latest. FYI I have a couple of Carver M500t amps as well as the matching professional processors and have a TGP...got tired of the expensive path...now have a Lexicon...should have listened to my advisors years ago. If you take the Sunfire Amp apart you will see how it is built. If you bench it and try to push it full throttle with big surges, you may find it cannot hold it output. Take a look at it and note that the components are smaller, lighter than most high end. Most often people do not need all the power for long intervals; thus, Bob found a means for getting it just long enough to keep most happy, to pass the power ratings tests and to market the item. Not knocking hte design, just saying there is a reason it is lighter and there is no free lunch.