Importance of Amplifier versus Preamp?

I don't want to seem picayune, but it can be important to be precise about model numbers, in part so that others can research what you've got. So I believe a couple of corrections to your correction are called for:

SAE 2101 should be SAE 2401, as you stated earlier.
Sony TA-E330ES should be (I believe) Sony TA-N330ES.

I'm not particularly knowledgeable about bookshelf speakers, but among vintage speakers one brand I would suggest looking for is ADS, also referred to as a/d/s.

Good luck. Regards,
-- Al

The amps have specs that are likely not a lot different from high end amps.

The preamp however is a different matter- I would seriously look for a budget tube preamp for this setup- that would offer the most bang for the buck in terms of improvement in sound, if the tube preamp is in good working order.

FWIW, I just bought and set up a pair of stand mount monitors from Music Direct (Wharfedale Dentons at half price ($500). I used a tube amp and they sound far beyond my expectations. They are well reviewed in the English mag's. Caveat - they are rear ported and won't sound too good backed up to a wall.

It is often said that your amplifier is the engine of your system, and the preamp is the heart. Both are important and should work synergistically. I previously ran a Boulder 1060 amp with a heavily modded Ayon CD-5s as linestage and that combo worked very well. With that said, the Boulder had a bigger influence over the sound. Same deal with my previous Classe power amp. So i'd have to give more weight to the power amp, then pre. With pre/power combo's I generally prefer a ss power amp with a tubed linestage which gives you the option to roll the stock tubes with better matched NOS tubes (unless we're talking about Vitus, Soulution or Goldmund).

Another option to consider is a good integrated amp. There are some really nice integrateds out there which can be had at a bargain 2nd hand such as Hegel, Luxman, Modwright, Simaudio Moon Evo and Musical Fidelity, as well as tubed integrateds such as Vac & Leben.

It's an easy experiment.
First try running without an amp.

Then try without a preamp

Which is more important will become perfectly clear.