Nuforce Ref 9 SE

I bought my Nuforce 9SE v3 from a dealer that is driving a pair of ribbon speakers. The amps themselves are not bright but very detailed and have a wonderful spacious soundstage. They seem to be best mated to tube pre-amps and are only at their best using very good power cords. That said, you would be hard pressed to get better sound for anything less than 10k. No kidding.
A good friend of mine is driving his Revel Sudio 2 speakers with the Nuforce amps with a Benchmark DAC. His preamp is the top of the line Joule Electra (amazing piece of hardware). The DAC had a bit of edge and lack of music detail compared to my MSB Power DAC. (so much for a rating of Class A from the reviewers).
If you want the best sound get a preamp in my opinion. A good one will transform your system to a level you would not believe. Just my opinion.

Your list is all linear solid state amplifiers, sort of apples and oranges. Like tube and solid state amplifiers class D amplifiers have similar class characteristics as well as individual presentations.

Linear solid state designs typically begin to lose their charm as they get pushed beyond a certain output level, which is usually quite high depending on the load. Switching amplifiers tend to maintain their level of performance until they reach their limit.

My 9SE's are driving 87dB 4ohm Eidolons and have yet to run the SE's out of steam. I found that my SE's benefited a great deal from upgrading my AC with dedicated circuits using metal clad wire runs to the outlet and using shielded AC cable from outlet to the amps. This is a relitivly inexpensive upgrade that any system would benefit from.

I don't believe there is a tube preamplifier made that can match the quite transparency of most class D amplifiers. If the idea of using a tube pre to ease a sonic concern with a class D amp, there is usually a problem elsewhere in the system. IMO a battery powered preamp is the ultimate companion to a switching amplifier. Switching amplifiers can magnify time and phase issues of many poorly designed speaker systems as well as AC issues. I think this is what most casual switching amp users dislike and why they find the amp clinical.

On the other hand tubed output stages of source components can sound stunning as well as pairing the SE's with preamplification of a much higher class. The Benchmarks attenuation will work but I would suggest auditioning a stand alone preamp for the sake of comparison.

I use a tubed preamp with my SE V3s and my music preference is vinyl analog for sit down listening. I could not be any happier with that combo. I dont think you should have any problems with what you described. For Nuforce products you do have a choice they offer a 30 day in home audition for a buck listen first then decide.
Good luck
Mike