pioneer premier and alpine are some of the best out imo. i did hear that the new alpine's with the touch glide feature are difficult to use and that alpine has had problems with these ones' so far.
Preamp Output Voltage The output voltage of the receiver's preamp outputs. Higher preamp output voltage can mean cleaner sound (better noise resistance) and higher output from your amp.
The Glide Touch feature on the Alpine HUs isn't really difficult to use at all. It takes a day or two to get accustomed to using it, but it's not difficult.