Looking for how to best structure classified listing for 3 Chiro separates for sale

Hello all.  First time user.  I just created the following listing yesterday:  https://www.audiogon.com/listings/solid-state-chiro-c-500-c-800-c-5-1-2017-01-22-preamplifiers-18080...

Is there a better way to structure this single classified listing for these three pieces since I'm looking to sell them as a set?  (I just arbitrarily selected the Preamp category)  Also, are there any other sites out there on which you would recommending posting this listing?

Thanks in advance!