Seeking Advice on NOS DAC

The Comet being discussed is quite far from the NOS sound. The two overarching characters of NOS are timing precision(could be called ease) and treble roll-off, the later being addressed by forward correction in many new production units.

The Comet has a slightly bottom up sound, a richness to it, which makes it pleasing to the ear however the timing performance is lacking due to the use of a minimal phase filter. Its worth saying that this trait may only appear in single-driver systems. I'd call it neither laid-back nor aggressive in sound though it definitely falls to the side of intense colors & slight rounding of the bass.

The only NOS DAC I've had my hands on, and its old outdated tech now, stayed in my system for years despite a raw, mean, lean sound. It's magic trick was proper timing. Instant transients. Microdetail.

The debate is going to come down to what you personally find more relaxing. I've heard a number of modern OS DACs pull off tube tropes: color saturation, fullness, laid-back. Think of NOS more like a widebander in that yes they can tame treble nasties but they're more there for the raw textures and timbre picky. Personally I find timing errors more annoying than any frequency abberations so NOS ends up the sound that calls less attention to the fact it all started as electronic pulses.

Red, everything you've stated is consistent with my research, especially about timing or "ease." Every pro and user review loves the Comet, but NOS seems to have what I'm looking for.
Right now, the Audio Note and Hex are the contenders. But I need advice regarding a high output DAC going direct into my tube amp (1V input sensitivity).

This may be a silly question, but is it helpful to use a reclocker before the input to a R2R DAC? I know the reclocking device should not do any upsampling.

Low, regarding a USB/SPDIF converter, I use a Audiophilleo2 with the Pure Power supply between my MAC Mini with Pure Music playback to a Bryston BDA-1. They have come up used here on AG ocassionaly. The AP2W/PP should be had for under $400 used. 

I believe your 1V input sensitivity means your amp/amps achieve full output power with a 1V input.  This is relatively low and should work with about any DAC.  To me, the bigger issue is matching impedance if you are adjusting volume with a passive device.  This can be a significant issue and is probably why I am an advocate of preamps, even though mine is adjusted for unity gain (and buffered).
For example, the Jade and the Adagio (both with onboard volume adjustment) output 2V single-ended (rca) and 4V balanced (XLR) with the volume control handled by adjusting the reference voltage, which does not affect the signal.  Only a few high-end manufacturers (I can only think of Metrum and Empirical Audio right now) offer this type of volume adjustment when going sans-preamp - directly from DAC to amplifier. 
How do you adjust your volume if your DAC directly feeds your tube amp?