Class A preamp or Class A amp

Transistors need enough bias current to 'Wake them up' into their linear operating range. Higher bias levels will generate more heat and use more electricity. Since heat is the enemy of long life a cooler design may be wise.
Ron-C

I personally feel that your rig will be as good as the weakest link in the music signal chain. Two wrongs do *not* make a right in this hobby. To get the best possible sound, the "offending" component needs to removed totally & another better performing unit placed in there instead. There is no doubt that class-A pre & class-A power yields the most linear sound (I will not comment on 1 implementation of class-A vs. another) & if you can afford it as a *total* solution, then get that. Total solution includes electric bill for AC power & cooling. I have found that if the designer has decided to make a class-A amp right from the get-go then heat sinking is very well thought of rather than being an after-thought. Still, good ventilation is a requirement by the end-user.
Next best would be class-AB that are biased towards class-A for their initial watts such as Pass, Symphonic Line, Odyssey Stratos just to name a few I'm familiar with.
I quite certain that each piece in the music signal chain affects the overall sound. So, you decide where you want to compromise but don't let anyone tell you one piece has more or less effect than the other!
FWIW. IMHO. YMMV.

So the answer is Class A preamp and Class A/B amp that stays in Class A for at least several watts. I use my pair of Alephs in the summer as they're suspended from the cooler ceiling joists just under the speakers, both to keep them and me cool!