Maybe tube preamp

@markainsworth  I was working with Aric on an amplifier build. This was after receiving strong recommendations from @kdude66 and @teajay  
but I decided to hold off on it until I further solidify my digital front end and get the new speakers in system and settled.

If you can stretch your budget and get the upgraded parts you and Aric agree upon, that's what I would recommend. The preamp is a critical component (I recently learned this valuable lesson myself) and once you get a good one in system, you will realize that upping the quality reaps tremendous returns. Even if you stay to budget, the base build will go a long ways. Great thing about working with a builder like Aric is that you can have him perform the upgrades later. FYI: his current times to build are super short relative to some others out there and he doesn't over sell the upgrades; if anything he's likely to hold you back should you get crazy. : )

As for the 6SN7 linestage vs the Unlimited, Aric will be able to guide you on the differences and best fit for your needs and system. 

All the best.

One additional thought, given the infectious spiral of our hobby....it may be wise to look past your system...so you are better 'proofed' for the future.

Hi Mark take a serious look at Radu Tarta's DHT 4p1L tube preamp. I have owned one in the past and hope to get a custom one soon. Radu is a very talented builder and uses Lundahl transformers for power, choke and output. The link shows his most recent build with a $400.00 remote control. If you don't need a remote he will likely build one for you without it at a reduced cost.

https://simplepleasuretubeamps.wordpress.com/products/  

Just to add to what david_ten said, going down the Aric's path, or any one-man builder shop for that matter, is a very different mind set as compared with the big guys and going off the shelf. He's literally one email away and (obviously) knows his gear inside out. You just need to tell him what type of sound you're after and he can tell you what parts to use, down to which capacitors and exactly what values. You can do that as a recipe for him to build to or implement the upgrades yourself after purchase. I personally find that very refreshing and can forego the fancy esthetics of a comparably priced, possibly used one at that, a name brand piece. For example, I'm a soundstage and an air-around-instruments junkie and the replacement/upgraded capacitors he recommended were higher in chain of the same brand but different values from what he'd in the unit. All based on his experience. Like everything there's always a trade off so if I preferred more bass he might have recommended a different brand and/or value. For me, it was fun to pull out my long forgotten soldering gun and ordered the components myself and the self satisfaction was really enjoyable. I could have spent a lot more than the price of the preamp just for the upgraded capacitors and that's where the experience of the builder comes in to inject sanity. The irony is many of the real pricy gears out there use real cheap components and a good chunk of the price of admission goes for the esthetics and all the machining of the case and the fancy knobs. 
Anyway, like I said, the good news is there are lots of options out there, and at any price point, both for the gear and the path of upgrades one is willing to take. 
Make sure you let us know what you decide.

I just bought a Schiit Freya, which I didn't need and hasn't arrived yet. It's so inexpensive I simply had to try one as no other preamp I've heard of has its features, and I wanted a tube preamp to go with my SEP power amp. It comes with one fancy knob.