I get the benefit of the analogue start, but just not convinced an in/out to multitrack is good? I can just about get it going to a stereo machine with wide tracks and top-notch s/n, but 24 on 2" is a bit worse?
The point is that it's not just a back-n-forth conversion...which would be kinda dumb.
What happens is that you bring 24 tracks out from the DAW...and then you are mixing and processing them in the analog domain, and then mixing down to stereo before going back to digital, so the multi "conversion" thing is irrelevant...the tracks/mix are being changed by the analog mixing and the analog processing.
If you were going to just convert back-n-forth without doing anything...then there might be some loss, though TBH, at the higher rates and bit depth, I doubt anyone would really hear it.
I've only been able to do 24 track transfers for the last few months but around 70% of the 24 track tapes have had Dolby A on at least some, if not all the tracks.
Not sure which decks 2" multi-track decks used Dolby A...?...but the best NR option which is common for many pro decks is Dolby SR. That stuff is as good as NR gets. It's a pretty expensive setup, and not something that's built into any decks AFIK...rather it's an external system, fairly large.
I considered a couple of times when I saw some available system (not very common on the used market)...but TBH, I've been running my deck at 15 ips without any NR, and it's extremely quiet. I've had people surprised at how quite the tape was when they listened to the tracks where there was no audio signal.
None of the usual hiss you get with many decks without NR. I know my old Fostex G16 1/2" was pretty hissy without the Dolby C...and with it, there was a noticeable "dulling" to my ears. My 2" retains all the clarity without the use of any NR.
I've only tried it a couple of times at 30 ips...but I never compared the S/N differences. I just like the punch of the 15 ips more...plus it saves on the tape.
I know the heads on my deck were re-lapped and optically aligned by JRF Magnetics...and I've done the full calibration to it, and pretty much I stick with 499 tape, though I also have some 456 and 911 reels. I forget where I set the bias for the 499...not for super hot use, but I do track with pretty robust signals always, since the 499 can handle them easily, but I don't do that for the sake of the S/N...this deck just seems to be unusually quiet.
I'll have to see how it sounds with the 456...but I'm expecting it will still show good S/N.
My deck has built in Dolby HX Pro noise reduction...but I never saw a need for it, and I prefer the sound without it. It's not anything special.