Amp and Preamp recommendations for Yamaha NS5000


Currently have SOTM 200 ultra -> denafrips terminator +dsp board -> Audio gd he9 pre amp -> dual bryston 4bsst -> NS5000.
I am loving the sound... just sounds incredible. But wonder about amp and pre amp upgrades down the road. Any thoughts on what might work well? These speakers are 87 db efficient.
So far thinking all pass labs amps + pre.

Ok with buying used. Would like to keep things under $20k if I can. Thanks.
smodtactical
A Supratek DHT preamp would do the NS5000s justice.Say a Cabernet 300B/45 .Well worth trying with your Bryston power amps.
Other interesting integrated are Absolare (great sound) and Aavik.

Absolare (no dac, tubed input)
https://www.absolare.com/integratedAmplifier.html

Aavik (has dac). I have only hear another Aavik model but this is the newest
https://aavik-acoustics.com/products/u-380.html
As I said to yyz in dm. I may go from dual 4bsst (with sst2 mobo) to a single 14bsst2 with not much investment for the change. Hope thats not a side grade.
I mentioned to smodtactical that I thought it would be an upgrade from 4B-SST to 14B-SST2 for 2 reasons. 

1) The SST line is a little coarse on top. I owned 4B-SST, PowerPac 300, and 7B-SST for many years with various speakers, I know Bryston. The SST2 line is a little smoother on top and will be appreciated by the NS5000.

2) Going from 4B to the more powerful 7B was beneficial with my inefficient Revel Salon 1 in a big way. I also had a large room and played it loud those days (ah the memories). Not sure if the NS5000 needs that
much power or if the OP plays his system loud.

The 14B-SST2 is almost as good as the 7B-SST2. The 7B is slightly better because it is housed in 2 chassis which provides some slight spec increases.