Are you talking about the slider in Preferences > Driver Settings > Mixing Latency?
Or do you mean the slider in the QUAD-CAPTURE ASIO control panel Driver > Driver Settings > Audio Buffer Size?
If it is any help, I have a QUAD-CAPTURE and I am currently running in ASIO mode with an Audio Buffer Size = 4. This gives me an input latency of 3.3 milliseconds (144 samples), and output latency of 6.6 milliseconds (290 samples) and a roundtrip of 9.8 milliseconds (434 samples).
I record in 24 bit and 44.1 kHz
The above settings provide me with a reasonable delay when recording.
I have never tried the QUAD-CAPTURE in WDM/KS mode
cheers
andy