Two things to try
First and easiest 2 rca y-cables male to 2 female half goes to your amp the other half to your t30
second yes they do make two 1/4" to 1/8" jacks as well as two xlr to 1/8" You want female XLR
3.5mm xlr, Pro Audio, Musical Instruments items on eBay.com
I checked around everyone is selling wrongly wired cables or is charging WAYYYYY too much B&H wanted $60 for the cable.