IRS Beta Bass Amp - Class D?

Recent acquisition of very very nice IRS Betas
I am building a front end from scratch 
I am going with a Sonic Frontiers Power 2 (sovtek KT88s)
Possibly Transparent Audio Reference cables to the mid/highs
Recommendations on bass amplification?
I currently run vintage Mac tubes on several systems, but I want something that will be strong and effortless without spending more than say $2k.
I am also considering class d, I have had extensive maintenance on my macs due to
age (worth it!!) but would prefer to avoind that in a SS....so new stuff? Old stuff?

Also, I live in a rural area, there is sOme local availability but, I have a 5 hour drive to SF.

Respectfully,
Walt