The room is the most cost effective measure for good listening experience - I prefer just a lot of book shelfs full of random sized books and phase gradient diffusers on the ceiling - which are a specialty item that you can find from companies that do acoustic room treatments - Armstrong Ceilings in one company has a few that look attractive, As far as snake oil or should I say cables - keep them short and a good stranded cable of 12 gauge (or something that will take 15 amps or so) from what Dr Toole had mentioned in his book, a 12 gauge stranded wire will loose around 1db over a 65 foot span. if you need to run a line at 60' + then either thicker cable or make your own using thin strips of copper foil laminated together between Mylar or Kapton - Mylar is way cheaper. this will allow the capacitance and inductance to basically cancel each other out. The ultimate cable is the Transposed Litz Cable, use in high frequency reactors and transformers - but that's an overkill. Cables are the least likely to effect your sound in comparison to things like dirty power, bad speakers and or placements and especially bad room acoustics.
but getting good cables for the preamp stage is way more important. in the studio environment where I do most of my work - having double conductor balanced cables (4 conductors instead of three) is now used in pro studios. The movement of wires inside a cable does effect the sound quality when you move them around, and this is caused by changes in capacitance between the live conductor and ground. with 4 conductors and movement in the live wire gets cancelled out (for the most part) chance are you will not hear that issue because consumers don't use condenser mic which have a rather low levels in comparison to line level signals that a preamp would produce. but it help out
one snake oil that works quite well is Stabilant 22, which has been around for at least 35 years or so. these improve connections of low level signals _ basically in the nano scale, the material will conduct when an electrical field is present, such that connections that are very small (like 1/4 jacks or RCA) will have a very small footprint where it connects. if you have a lot of connections (like ones found in recording studios -just think patch bays) then you really start to hear it. the best cure for this is to eliminate as many connections as possible. You can find Stabilant 22 on ebay. I knew the inventor who was a member of the AES in Toronto (the same AES that Dr Toole is a member of)
Just getting Dr Toole's book -" Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms", will be your most effective tool for all things audio. there is nobody in the world that has done that amount of research in psychoacoustics then him. His book is the bible of understanding what good sound really is. I've known him from the AES in Toronto for about 35 years.