Look for an EVS(Electronic Visionary Systems)passive produced by Rick Schultz some years back. It retailed for around $450 new and it's about as clean and transparent as you're going to get.
I owned it, a couple Reference Line models, and an old McCormack or was it Mod Squad back then? At any rate the EVS used a pair of stepped attenuators for gain and balance and had a "straight thru" mode where the only thing in the signal path was a couple RCA's coming and going, a very short piece of wire and one or two resistors. Can't get much simpler than that. It was by far the best sounding passive I've heard.
I owned it, a couple Reference Line models, and an old McCormack or was it Mod Squad back then? At any rate the EVS used a pair of stepped attenuators for gain and balance and had a "straight thru" mode where the only thing in the signal path was a couple RCA's coming and going, a very short piece of wire and one or two resistors. Can't get much simpler than that. It was by far the best sounding passive I've heard.