I agree with K_peterso above on the bright and harsh sound from the Genki preamp. I just wanted to warn you that I've had an equally bad experience with the Kollector pre-amp. I would advise you to keep it out of your upgrade plan (if ever you considered it).
For me, the Genki/Kollector combo made listening a less than pleasant experience because of the harsh, gritty high frequency sound. I played with it for over a year, by trying different cables and such. Only after upgrading the pre-amp did I realize just how poor the Kollector sounds... night and day. Although it is very versatile, I wouldn't be surprised if the Kollector uses the same amplifier circuits as the Genki's built in pre-amp.
Good luck,
Bruno