Nobody has voted yet? People here are so indecisive.
I haven't yet built the GAP for 5.8 SOHO but I generally build it about twice a week for Slackware (from SVN). The GAP uses 'wavplay' for its audio output. WAVPLAY is an ancient tool that is more likely to be found on a ten-year old BSD system than any Linux box. It can be made to work on Linux -- I have done so in the past -- but unless you need it for your animations, it is not really worth the effort. My recommendation would be to pass '--disable-audio-support' to your ./configure and not worry about it for now.
I have 5.8 SOHO on a dual boot system but I won't have access to it until tomorrow. I will look into building the GAP for it (and even investigate getting WAVPLAY to work). If you need help before then, please provide a bit more details about the errors you are receiving and I will try to get back to you.