what impacts the sound quality more amp or pre-amp

Are you sure that you want to rule out an integrated?
Personaly, I don't consider separates unless I am prepared to spend thousands, at least couple of them.

The Alon II speakers are specified as 87 db efficient and are, I think, 4 ohm nominal impedance. This is a difficult load for most tube amplifiers to drive.

My personal feeling is that if you want tube sound that you should go with a tube amplifier. I think this makes the most difference. But it implies certain speaker choices too.

From a practical point of view, it is going to be challenging to find a tube amplifier for $500 - $800 which will be able to reasonably drive your speakers.

In the context of your system and with your budget, my feeling is that a tube preamp would be your best bet.

The Mapletree Audio Line 2A SE preamp is $760 new. It will likely survive many system changes and upgrades that may or may not be in your future.

"The Alon II speakers are specified as 87 db efficient and are, I think, 4 ohm nominal impedance. This is a difficult load for most tube amplifiers to drive."
No mention is made of phase. This would be the deal breaker for tubes, that and wide swings in impedance.

4ohm and 87db are nice, but not deal breakers for tubes. Harbeth, less sensitive and considered tube friendly.

Tube amp choice, however, DOES imply certain speaker choice.

pre is the heart of the system. As said balancing it all out helps more.

I think the choice of speaker and then the choosing the amp
to drive them is the most important choices in building a
system; other than the recording and the room, they will
have the biggest impact on the overall sound of your system
- the change brought by digital source and preamp, while
important do not make nearly as much of a difference as the
amp/speaker in my experience. I also agree with Wilysnet
recommendation on an excellent tube preamp selling for a
fraction of the cost of its acoustic competition, though if
I had a tube amp I would go with the even less expensive
Lightspeed Attenuator $450 which is the best sounding volume
control tool I have ever heard if well matched to an amp
(though not very flexible with only one input/output, and no
remote control.

So yes, everything is important....but the amp/speaker is
critical and the most defining pairing for what you system
sounds like. Once you get that right, the rest is relatively
easy (though not foolproof).