formal wrote:This might help answer some questions on cables and inputs. As far as I know to get the best sound quality you will want the connector with the most metal to conduct the current/signal. RCA inputs seem to be used because they are more durable than 1/4" and cheaper as well. It has always been that the more expensive gear uses 1/4" while the cheaper gear uses RCA. In the case of headphone out VS RCA out, I think you will get similar quality if you use the 1/8" to 1/4" adapter. Your best bet would be a 1/4" stereo cable to minimize signal loss. As always, the shorter the cable, the better.
I'd like to add, the main reason to use 1/4" TRS connectors (apart from tradition) is because you can use switched jacks, where plugging in a plug breaks a pre-made connection and establishes a new one (involving the signal you are plugging in). Can't do that with RCA. Also, with 1/4" you can use stereo jacks for symetric signals, which reduces quality loss and interference pickup greatly, especially for long cables of 5 or more meters. Also, 1/4" is much more robust mechanically.
Anytime you don't need long cables nor outstanding robustness nor switched jacks, RCA does the job perfectly fine. Just don't use those cheapass ultra thin wires you get supplied with cheap stereos or cd players.