From my relatively short experience . . . . .
Power amplifier - Neutral
Source/DAC - Neutral
Speakers - Neutral
Preamp - whatever you like - warm, lush, rich, revealing, transparent or indeed neutral etc.
It's where preferences and tweaks can be made most noticeably to the system. In an ideal scenario all of it would be 'neutral' (of no character) but our ears (senses) aren't all stimulated by the same things (objective sound).
Until I settled on the 'right' (for me) combination of tubes/caps etc for this particular preamp I had 3-4 other amplifiers around just in case and as a reference. Class A, tube, integrated, class D. With this preamp and this power amp they are all sold/for sale.
Room acoustics also play a part in this, a neutral amplifier (preamp/whatever) may sound way too harsh in a 'sharp' acoustic environment. Changing to a warmer/lusher sounding one (maybe rolled off/distorted) may be exactly what the room (and therefore in this case 'the system') requires. At least in the interests of listener satisfaction. At this point measurements and accuracy are a fallacy. They give you the information straight and true, if you don't actually like listening to this information (accurate or not) then there is no point in chasing it really is there?
Depends what you're in it for really.
Personally accuracy/transparency has gotten me very close to where I want to be (huge fan of Quad 57/63's) but had I been simply wanting to increase accuracy/transparency I certainly wouldn't have settled on this preamp. That would have been a mistake as far as my listener satisfaction is concerned.
System 1: - Amp - Musical Paradise MP-701 mk2 - Neurochrome 686
- Source: Audio Technica LP-5 - Custom 6V6 stage - Novafidelity X30 - Soekris 1421 (LPSU) - Custom TDA1541 C3G DAC -
- Speakers: Martin Logan Prodigy's - Subs: - REL T3's -
System 2 - Amp: Musical Paradise MP 303/Custom 300B SET - Custom 6SL7 Pre -
- Source: Pioneer N-30K - SONCOZ SGD1 -
- Speakers: Loth X BS1's - Sub: REL T3 -