I never heard any degradation but I am sure someone will say that is a heresy and you should be tortured.
Tortured is a bit strong, I would think a mild slapping around would suffice.
All wires and all connectors will
technically affect and color the sound. Whether this coloration will actually be audible to your ears with your equipment and cables is of course the question of the hour!
I would avoid the obvious el-cheapo marginal-quality typified by the budget $0.49 Monoprice
Audioquest has some at ~ $20/pair, but I don't know if they're any better than other imported machined adapters at $5 - $10/pair.
The nicest
looking ones I've come across are the
ViaBlue XS 40615/40620. I haven't seen them in person, but I do have some other ViaBlue connectors and their German metallurgy, machining and plating is excellent quality and more comparable to entry-level WBT and Furutech than to typical Asian imports.
Unfortunately, unlike other ViaBlue connectors, I haven't seen these offered for sale in the U.S. and the only source I'm finding is eBaying them from Germany at ~ $25/pair shipped.
Of course, if you're not using exotic cables, you could also have someone like Markertek make you up some cables with industry standard Neutrik or Switchcraft right-angle RCA connectors and Belden or Mogami cable of your choice and forgo adapters all together.
Steve
