Thanks! I'm glad to hear that it can do the clean preamp output. I never saw info on this anywhere when shopping.
If you don't mind me asking how do you like that XTZ Edge amp vs the Denon amp on your mains? I actually love the Denon, but I'm mildly curious what an external amp might sound like.
Among modern, well-designed amps, you should not expect amps to provide an audible difference unless:
1) One of the amps is defective
2) The amp was of abnormally poor design (not something I would expect from Denon or XTZ!).
3) The amp uses tubes to deliberately color the sound (this is common with guitar amps)!
4) You speakers, music, and listening levels require more watts/current than the amp is capable/designed to deliver!
5) One amp is set to play louder than the other (we always like the sound a bit louder-within reason)
Think about it! A good amp from the late 60's is still a good amp today (if it has been reconditioned as needed). The technology to design amps has been mature for many decades! there are some new twists, but generally speaking you typical Class A/B amp has no excuse not to work at a level well beyond your ability to hear any defect.
If a company is adopting a preferred sound signature (which seems to be what some reviewers indicate), then, by definition, they are choosing to introduce some degree of distortion into the signal.
As I said earlier, Guitar players often deliberately choose an amp that "fleshes out" the sound of their guitar by adding harmonics, especially if in a smaller group. This is akin to my voice sounding better in the shower/bathroom. But you want to let the musicians determine how they want to sound, not your amp! If such an amp was used for music with many many voices, it becomes a jumbled mess! Good musicians know when to "flesh out" their sound and when to clean it up to make an overall best presentation. You would not want an amp to categorically do that in your home system!
Many times, with speakers (which is not yet a mature science - many decisions speaker designers make force them to sacrifice one aspect of performance for another), I have found a speaker that sounded "better than any other on a particular passage, only to find that it sounded worse on others. For example one of my favorite songs (that I use for auditions) is "Heart of the Sunrise" by Yes. It predominately features Chris Squire's bass. I listened to one speaker that put an extra emphasis on the mid to upper-bass region and this song sounded so fantastic on that speaker! However, later when I listened to "Time" by Pink Floyd, there is a place where both male and female voices are singing and I was horribly disappointed by how the male voices were far too dominant over the female voices - the balancing across frequencies was wrong in a way that was admittedly nice with bass-centric music, but otherwise was not right for more typical music!
So pick a speaker that has the sound you want, tweak it with the pre-pro (if needed), but don't look to your amplifier to do anything to the sound. The only real question with an amp for a reputable manufacturer should be "Is it capable of driving my speakers at the levels I want to listen?".
Generally the answer to that is a yes if you are mid-range or higher AVRs, but there are some speakers that will make a liar out of me because they demand power with impedance dips well below 4 ohms accompanied by difficult phases. Usually a good review (which should include measurements of impedance and phase) gives you a fair assessment of what type of amplification you need.
Honestly if I go into a showroom and you have a simple box on one side and an over-sized amp with big meters on the other side (and assuming the 5 items I listed above are in compliance), I will hear the amp with the meters sound better - I can't help it, but if you blind-fold me and don't tell me which is which, I will not be able to consistently identify the amp that was so clearly better when I knew what they were - such is human perception.
Here is a fun example of how our expectation colors our perception:
