>A Type IV "metal" tape with Dolby S and recorded using HX-Pro can sound seriously good
We had one of those 3 head tape decks growing up. The one we had a yamaha with dolby hx-pro,b,c and dbx. We used to tape cds and try to a/b compare them.
The 3 heads were erase, record and play, which meant you could monitor the recording as it was happening and adjust levels and such. (and results in the weird behavior of the "tape monitor" button on amplifiers).
With Cr2 tapes (not as good as metal, better than normal) and dbx noise reduction it was really hard to tell the difference between cds and tapes.
The quiet parts on tape clearly had hiss without the noise reduction and the dbx noise reduction made the tape sound like crap in your walkman, so we just used dolby C most of the time. The walkman was always the weak link, without cleaning those rubber rollers you could get some weird speed ups and slow downs on playback ("tilt a whirl effect").