And how to you such sound cards as ESI Juli@ and Infrasonic Quartet?
Esi Juli@ needs external instrumental (mic/instrument) preamp, it has only line inputs. I`m using Juli@ with Digilab SPM-100 (russian made, far better than cheap Art`s preamps, but price is similar to Juli@).
As for Quartet, it has Hi-Z input, but impedance is very low (150 kOhm).
http://www.infra-sonic.com/site/p_PCI_quartet.php
Also there is complaints about levels of Hi-Z, level pad is switched by jumper, so you can have to low or to strong (when clipping occurs) level, nothing between. So, basically, some people arrives to solution with external mic/instrument pre, bypassing internal preamps.
As another alternative there is
M-Audio Fast Track MKII
Rather good maximum input level on Hi-Z (+12 dbV/+14.2 dbu), 1 MOhm impedance, phantom power for condensers.
As for Line6 stuff it`s shame that they not specify inputs parameters (maximum input level before clipping).