Best preamp (used or new) under $350???

I'm thinking of upgrading my preamp but have a budget of about $350. I currently am running a Schiit SYS. I'm happy with it but it only has 2 inputs and I would also like a remote for volume. I'm considering the Schiit Saga but would like to inquire with the forum if there are others that I should consider?  I could buy new or used so please let me know your thoughts. 

The other pieces in my system are a Red Dragon S500 power amp, Sonos Connect, Onix XCD88 CD player. I'll also be connecting my tv via a SMSL Sanskrit DAC. Speakers are Kef ls50. 
Used Yamaha?
Any particular models?

If you want strictly a 2-channel preamp, you are probably looking at some sort of really old NAD or Adcom.  However, if you look at the bargain basement home theater processors, you can get a real gem.  The HT Processors really don't keep their value at all because of the perception that you need the latest and greatest digital decoding / HDMI2.0 / Atmos, room correction, etc. etc.  As a result, the value drops like crazy the older they get (this is not like 2-channel audio!!!)  The older HT processors can be used as an extraordinary preamp for the money.

On Audiogon, there's a used Krell Showcase for $200.  There's also a Rotel RSX-1058 for $325.  The Rotel is newer, of course, so the long term reliability may be a lot better and it supports a lot of new formats (HDMI).  However, the Krell processor uses their fully discrete Class A analog circuits and also has balanced XLR outputs.  You would probably need to hook these up to a television/panel to configure it, but once it's configured, all you need is the remote to adjust source and volume.

You can also use these as DACs that can actually be superior to many other 2-channel DACs. 

I used a Krell HTS 7.1 for 15 years before it finally died.  It beat the crap out of several other items that I tested and I continued to keep it even though it did not support newer digital formats.  The Krell was limited to digital coax (which means old school compressed Dolby Digital and DTS), but it still sounded better than the hi-res bluray audio through an Emotiva processor -- proving that the newer hi-res formats are not necessarily a silver bullet.

If you want a small footprint, the Parasound Zpre2?  It's currently on sale (brand new) at Audio Advisor for $277 (regular $399).
i'd second the zpre; you can also find rotel 1070 or 970 at that range
Your Red Dragon S500 will love a tube preamp in front of it!
Look at used Parasound P3 if you can find one.
Hi, I retired a B and K reference 50 HT processor, all analog, about a year ago. I Have it going on 12 years or so.Great as a pre amp.  Going to set it up in a spare room. They are well made and received great reviews. I've seen them on Ebay/ Audiogon for as low as $250.  just thought I'd mention it. Enjoy your music!
Just checked Ebay. They are selling for $200 or less.  almost give'n them away! 
Excellent passive pre from Tisbury Audio...I use one in my second system & it's superb.
McCormack Micro Line Drive preamp Go for about $300 or a bit less.    Transparent !
  Best preamp (used or new) under $350???

Used Schiit Freya, should be around that second hand
1: Remote, using a great 128 relay control volume control ,
2: 3 x inputs,
3: Choice or SE or Balanced input/outputs,
4: 3 x different selectable output buffer stages, tube. Fet s/s or passive.

Cheers George
I'm using the Schiit SYS and I'm most pleased w/it. Before purchasing the SYS, I considered the Tisbury and the Zpre2. If you can find a Rotel RC-972 pre-amp I strongly suggest you purchase. I've owned a few Rotel pre-amps and IMO, the RC-972 is fantastic. (I found it better than the RC-995.) Remote and plenty of inputs. 2 pre-amp outs. No phono and no balance control. It's a pleasure listening to the RC-972. 
Thanks for the ideas. There’s some models that I hadn’t thought of and that idea of using an older HT processor is great, but dang those things are so bulky!  Please keep sending ideas. Any tubed ideas?
You should be able to find a used one here on AG. Given your system I would continue to search for a 2 channel pre.
Acurus RL-11
Acurus LS-11
I recently bought a Jolida JD 5t tube preamp for around 400. I realize it's over there 350 mark,  but what the hell it's 50 bucks. It's the Best pre I've heard in a long time. In my humble opinion, it would best anything in the three to four hundred range from NAD, B&K, adcom or parasound. I actually bought it for my sister, and now I'm super jealous and can't wait to buy one for my self. Seriously it will blow your mind how good it is.
I would also agree with the McCormack line drive, those are very good as well.
I think an older NAD pre, like a 1240, 1130 etc. are some of the best bangs for the buck, but the buck is usually around $75-100. So, take that into account. However, jt will get you through with very good sound until you can and inevitably put together a budget for an upgrade.
Check out the Classe CP-35 offered here on AG for $325.
Possibly keep your eyes open for a NAD c160 or c162. They should be well within your budget. They also have a pretty good phono stage as well. Happy hunting!
Don't know if you have made a decision,  but I'd keep this in the mix.  Brand new, of course it isn't a MBL6010D,  but I've seen the boards in both and have to say that they do look like a direct knock off.  I suspect this would be superb at its price point. 
I hope this helps, Tim