There are reasons you might prefer your RCA cables over XLR. One is that some XLR hookups on consumer equipment are not true balanced circuits. In other words, they equipment manufacturer has "faked it" in order to cash in on a trend in this area. A poorly faked circuit could sound worse.
Even with a true balanced circuit, a XLR connection typically has higher output (6 dB) than a single ended RCA connection. At worst this could overload the input circuit of the preamp or amp which would give a noticeable edge to the sound. At the other end, it may still be clean, but it might have you listening louder than you normally might due to where you are visually inclined to set your volume control. These factors would need to be closely examined before declaring a true sonic difference in the cables or cable format themselves.
I'm in the camp that when we hear a true difference (not a psychological one) there are always technical factors that can explain. They may not be the obvious or trendy explanations, but there will be an answer somewhere.
Even with a true balanced circuit, a XLR connection typically has higher output (6 dB) than a single ended RCA connection. At worst this could overload the input circuit of the preamp or amp which would give a noticeable edge to the sound. At the other end, it may still be clean, but it might have you listening louder than you normally might due to where you are visually inclined to set your volume control. These factors would need to be closely examined before declaring a true sonic difference in the cables or cable format themselves.
I'm in the camp that when we hear a true difference (not a psychological one) there are always technical factors that can explain. They may not be the obvious or trendy explanations, but there will be an answer somewhere.