I have had my S4, new since release.
Loved it, one of my best techy purchases I have ever made, everything worked great except trying to integrate my 1210s. The sound coming from the phono channels was just not at the standard for mixing vinyl and digital together. (I did have phono correctly selected and highlighted on the S4)
I know I had them set-up correctly, tried every avenue to rectify but finally just resigned to mixing vinyl on my old Vestax mixer and digital on the S4.
Fast forward to this year and decided to upgrade my old Vestax mixer to a Xone 24C.
I tried some Xone / Traktor integration, the DVS system worked flawlessly with the Xone, smooth as butter. The S4 with DVS was always too patchy to use reliably.
Then I switched the master output of the S4 into the left channel of the Xone, set Trakor to external mixer mode. bingo after 8 years I finally have a system where the quality of digital and vinyl are closely matched.
The Xone's two channels can be switched to Phono / USB / Line, so can mix
Phono (Left TT) to / from Phono (Right TT) (Vinyl mix)
Phono (Left TT) to USB (S4 Deck B) (Vinyl to digital mix)
USB (S4 Deck A) to / from USB (S4 Deck B) (Digital mix)
Phono (Right TT) to / from USB (S4 Deck A) (Vinyl to digital mix)
All of these modes are recordable via the trakror s/w.
FX can still be applied to each 'digital' channel including the S4 FX panel (need to enable in mixer options)
The beautiful Xone club filter can be applied to both turntable channels and the master out of the digital feed (so it cant be applied to a single digital channel if both are playing (if that makes sense)).
Some other things to note.
All mixing and sound levels are via the Xone.
I changed the xml settings of the S4 to have the same colour scheme as the Xone.
After writing war & peace, this is what I wanted to know, did anyone else have a bad experience plugging turntables into an S4?
I may have just had a faulty sound card, which would explain why it was also buggy using the S4 for DVS as well. If its a wider problem then the solution above worked for me.