I've had one of the RMA 1794 DACs for about 5 months now and love it! Mine has the National OP amps and a BNC input. I use the single ended RCA outputs because they sound better to me than the balanced XLR outs.
Prior to the RMA DAC, I had a stock PS Audio D-link III which I sold because it really didn't sound any better than the other digital sources I had, such as a Sony ES blu-ray, and Emotiva ERC-1.. The D3 did best the DAC in my Behringer DEQ2496, but not by much! The down-stream gear, consisting of a Cary Audio class D integrated, Jungson class A integrated and Gallo Acoustics Reference 3.1s certainly are capable of revealing differences between components, if those differences do, in fact, exist. After all the great buzz, I was surprissd the D3 didn't blow away my other sources, but it didn't and in the end, I couldn't justify keeping it.
Enter the Ross Martin Audio DAC... To be fair to the D3, since it was already gone before the Ross Martin DAC arrived, I couldn't do a direct comparison between the two, but if the D-3 had sounded this good I would have thought my $650.00 well spent and been thoroughly satisfied with the SQ of my system. Unlike the D3, the Ross Martin DAC, in the configuration I ordered, definitely does sound substantially better than the other digital sources listed above. You know how much fun it is to hear textures and effects etc. in familiar music that you've never noticed before, even though you've heard the music dozens or even hundreds of times? Well this DAC has that in spades and I can hardly tear myself away from listening these days. Even though it sounded very good right out of the box, it just keeps getting better, even now at 5 months out.
I suspect the word is getting out about these DACs and Ross might be inundated with orders. Any business person in this economy would naturally be cautious hiring workers and expanding their business and he may be trying to juggle it all by himself. I hope he doesn't burn himself out and I wish him much success because offering this much SQ for so few FRNs is a gift to those of us in this hobby. As the technology evolves I'll look forward to what he offers us in the future. BTW, It took about 2 weeks from order to arrival for mine.
All the usual caveats apply and I have no affiliation with Ross Martin Audio other than being a very impressed customer.