Tube Pre-amp Suggestions.

Another vote for Audio Research.  I have a SP9-MK2 and have been itching to get something newer and still haven’t pulled the trigger. Depending on you finances, the LS-28 is really good and of course there’s the REF series.

Oh and why are you wanting to sell 8 watts of Class A goodness?

The benefit to a reasonable tube preamp there are always better NOS tubes that will make it better or tune to your listening preference. 
I use Brent Jessee Recordings and Supplies on line. Super informative and probably knows my equipment better than I do

I see that not too many tube pres offer balanced inputs, any thoughts?

Among the three noteworthy alternatives, i.e., 1. Freya, 2. RP-7 and 3. VTL TL5.5 Series II Signature (2013), TL5.5 II Sig. has the best impedance matching feature.

https://www.stereophile.com/content/vtl-tl-55-series-ii-signature-line-preamplifier

This trio has received high praise from Stereophile, but impedance matching deserves careful consideration in the DAC → preamp → amp chain. The Freya has a low input impedance, while the RP-7 has a extremely high output impedance at low frequencies.

Quite happy with my Luxman CL38uc -it's at the top of your budget but you do see the odd one come up for sale. Tubes if you're that. I like the combo of a tube preamp and ss amp. If I've a complaint it's the lack luster remote for what that's worth. Otherwise no question regarding Luxman quality, both build and sound. Lots of "professional" reviews out there that are all positive. 

E.

https://aricaudio.com/tube-gear/
I’m using the Motherload XL with my Luxman M10X. I compared with the Luxman C900 and ended up selling it as I like the Motherload as it it is a warmer sound.

@aricaudio