Willsenton vs Billie MK 1

if you get a chance, please create a virtual system so others can see and give good advice. Until then, I will ask these questions in the dark. Do you have a subwoofer? If that is a no, I would look at that first because your Billie has good power for those 87db speakers of yours. With that being said when it comes to tube amps others on this site can give you much better advice. 

Sorry......Using Parasound as pre-amp......B&O sub. 95% streaming vis Node 2

It seems to have a decent impedance profile (though I have not seen a curve):
"The sensitivity as reported by Merlin is 87dB/W/m, and the impedance is 8 Ohms nominal with a 6.5 Ohms minimal rating."
https://enjoythemusic.com/magazine/equipment/0707/merlin_tsm_mme.htm

I'm not sure what you can spend, but the Quicksilver Mid Mono might be nice:

https://quicksilveraudio.com/products/midi-mono/

@troutbum - What are your feelings about the Billie amp and why do you want to change?  

I have had the Billie Mk2 in service for the last 2 years.  Driving Golden Ear BRX monitors.  It sounds good, not great.

Curious to your comments.

Rich 

I was interested in the amps made by Willsenton. I was not particularly put off by Chinese made tube amps since I have a Line Magnetic integrated tube amp now. The R8 was getting rave reviews and I was Iooking hard at the R800i. Then I saw a YouTube audio tech who reviewed these amps and found faults in the design of both amps. Upon looking further I had decided against the brand.