I have been pleased with the sound quality of my McIntosh C48 preamp. Imaging and low level detail are particularly good. Someone reportedly affiliated with McIntosh posted on another forum that the sound quality of the C48 and C50 are essentially the same, but the features differ (which should be expected for the $2000 price difference).
I have not compared my C48 to the C42 or C46 in listening tests. While the C46 has more equalizers the top one is centered at 4khz. I prefer having the top one centered at 10khz as on the C48, but rarely use the equalizer. The digital inputs on the C48 are very good and another potential advantage over the C46.
I have no complaints on the volume control on the C48. It is smooth in operation and displays precise control manually or by remote. Most of my listening occurs in the range of 30 to 45% on the display.
I have not compared my C48 to the C42 or C46 in listening tests. While the C46 has more equalizers the top one is centered at 4khz. I prefer having the top one centered at 10khz as on the C48, but rarely use the equalizer. The digital inputs on the C48 are very good and another potential advantage over the C46.
I have no complaints on the volume control on the C48. It is smooth in operation and displays precise control manually or by remote. Most of my listening occurs in the range of 30 to 45% on the display.