Finally...
Finally I could test all the 8 tracks on the TSR-8, and the DBX.
What I realized is that the DBX is really something I don't want to use with the TSR-8! The result, in term of sound quality and musicality, is somewhat "boring", it doesn't live (it's a personal feeling), while without the DBX enabled, the sound is absolutely great, brilliant, and very close to what I heard in the past on 24tracks/2" studio machines and big analog consoles.
Interestingly, I have compared the sound with the Tascam 238, and the TSR-8 sounds better in both cases. The sound is more briliant and "sings" more. On the other hand, DBX on the 238 seems to be better to my ears: it has a much more neutral effect than on the TSR-8, while reducing the noise very efficiently.
I have still a small issue with the TSR-8, which is the track 8. The recording level is very low compared to other tracks. I can notice it on the LED-meter even if I don't record. Is it a common problem?
Greets