Best Preamp to Pair with Acurus A-250 and Vandersteen 3 Signature Speakers

If I were you, hold off on selling that Acurus amp.

i disagree in this case

i would get whatever money you can from selling the acurus and put that towards something better sounding

the tubed preamp idea into the acurus, driving vandy 3a’s, is bad advice in my opinion.... you can spend alot of money on a tube preamp (good ones aren’t cheap) trying to feed the acurus and be worse off sonically and money-wise -- than going with a decent modern ss integrated

the vandy sig 3a is a smooth sounding speaker needing power and bass control, there are many fairly powerful, decent modern ss amps or integrated (ones without old school solid state sonic nasties) that will do very well and are more moderately priced than a good tubed linestage

in my recollection (i had both an acurus dia100 as well as an a250 power amp back in the day) acurus is classic early-gen solid state... raw power without any finesse... shrill lean sizzly gritty - i had totem 1 speakers at the time and the combo made my ears bleed

op - i am assuming your speakers are the vandy 3a signatures, right?

i would suggest getting a used odyssey or van alstine solid state amplifier ... for not too much more money they will sound much much better than the old acurus - or get a modern integrated with roughly 100 wpc if that can fit in your budget