I agree with Stanwal above. As you have already proven to yourself, the transport does make a difference. How much of a difference will depend upon the rest of your system.
In conjunction with trying to borrow/demo a top transport, I would also give the Cable Company a call, explain your situation and borrow some cables according to their advice. That would probably be the best place to start, give you the biggest bang for minimal dollars and the broadest exposure to many brands and types of cables. They are easy to work with when they're not too busy. Your most important cables in this case will probably be the interconnects from the transport, but you may hear other opinions as well - its really pretty system-dependent. Most importantly, trust your own ears. Hope this helps.
In conjunction with trying to borrow/demo a top transport, I would also give the Cable Company a call, explain your situation and borrow some cables according to their advice. That would probably be the best place to start, give you the biggest bang for minimal dollars and the broadest exposure to many brands and types of cables. They are easy to work with when they're not too busy. Your most important cables in this case will probably be the interconnects from the transport, but you may hear other opinions as well - its really pretty system-dependent. Most importantly, trust your own ears. Hope this helps.