just one question. If you would be an owner of a original (!) signed Jimmy Hendrix Album with clear history - no doubt about authenticity. If you decide to sell it - where would you sell it and would you buy and add a COA before, maybe from PSA/DNA?
Hendrix signed albums are super-rare, so they're a great topic to discuss. I'd get Epperson and PSA/DNA authentication if you were to sell it yourself. It's a 5-figure piece--if it's in good shape and has a strong autograph it could bring in the $20,000s or more--so paying even $500 for respected authentication will pay off.
RRAuction is a great choice, and their fees are a little less than many, but I wouldn't only consider consigning it to auction unless you can set a reserve and not be charged a fee if it doesn't reach it...and negotiate reduced fees. A piece like that would be a highlight of any auction.
You might do better putting the word out that it's available to reputable dealers active in that market and seeing if they have customers interested, and perhaps working on a 10%-15% commission. That way you might end up with more in your pocket, and there should be no surprises.