I don't know what you consider "cheap"... but the ones I use are the 'variable attenuators' [they're in my 'workbox'... but I'm not near the workbox or I'd look up the actual model number for you] from Shure. I think they were about $45- ea. from Banjo-Mart... but they are about as sonically transparent as anything I've ever encountered.
Best of luck with the search.