After reading the iAmp 800 needs +1/-1 I went to GC & SamAsh & a local music store. Talked to salespeople and looked at cables. Salesmen at GC & SA - "Haven't heard of +1/-1 - not aware of different speakon cables." Salesman at local music store - "Yes, we have instrument and speaker cables." Me - "Speakon is a type of cable" Salesman - "Sorry, we don't carry that brand." I have two speakon cables, one has a +1 on each plug - the other has no markings whatsoever. I did a search here and didn't find the answer. Can someone clear this up for me?