I also highly recommend the JVC Digifine line of head units. I have the KD-SH77 (identical to the 99 except MP3 capability) and love it. The 55 doesn't have as many features as the 77/99, but it has the same basic specs and capabilities.
Bob Johann
SoundQ SVT
1998 T-Red SVT Contour #3088
2001 IASCA Pro Street 1-600 Champion
2002 SLAP Pro Street 1-600 Champion
2002 MECA SQL Master Class Champion
2003 IASCA StreetX 1-600 Champion
2005 SLAP Expert Street Champion