Let’s look at the Audio-GD models:
NFB-29.28 : RCA output only
NFB-28.28 : RCA + XLR outputs
Internally, these two models are almost
exactly the same. The “28” model output
stage is engineered to work for XLR balanced output. This means that the “29” RCA-only model is a
tiny bit better when using RCA cables. In
your situations, this is pretty much splitting hairs and I don’t think you
would really notice the difference. You
would be better off getting the “28” RCA+XLR model so that you could support
both types of cables if you wanted.
As I said, the Yamaha HS80M only has XLR
and 1/4" TRS inputs. You can get
special RCA-to-TRS cables on ebay and other places. These are typically pro-audio cables and are
made by vendors such as HOSA or Mogami.
They will NOT be as good as Audioquest cables. HOSA cables are cheap. Mogami can be pretty okay (probably good
enough for your situation).
None of the audiophile cable makers will have
special RCA-to-TRS cables. You could
always have somebody chop the ends and wire them into TRS connectors, but it’s
more labor and money obviously. I think
it’s better just to get the “28” model so that you can get audiophile level XLR
cables to connect to the Yamaha monitors.
If you ended up already ordering the “29”
model and cannot change the order, you can try to get some Mogami RCA-to-TRS
cables. Or something on UK Ebay such as:
https://www.ebay.co.uk/itm/Pseudo-Balanced-RCA-Phono-to-TRS-Jack-Lead-PAIR-Van-Damme-Starquad-Cable/172382399235?hash=item2822caab03:m:mTnMtSg5Z26b_pog38jH39g
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As far as your preamp question, the
NFB-29.28 or NFB-28.28 are already preamps that have a DAC built-in. We call it a “preamp” because it has the
ability to adjust the volume up/down via the front panel knob or remote. You can get a separate preamp if you wanted,
but you don’t need to. It would just be
another element in the audio chain to affect/mold the sound.
There are some Audio-GD models that are
considered a DAC only because the output level is fixed (non-adjustable).
