Why are the vocals on some records hidden behind the music on my system?


Help! I am new to this forum, but have been into audio for over 45 years and have never had this problem before. I was lucky enough to come into some money and decided to use some of it to up grade my system for the first time in almost 30 yrs. The system consists of McIntosh MC-402, McIntosh C-100, McIntosh MCD-500, VPI HW19 MKIII, Soundsmith Aida, Furutech Ag-12 phono cable, Furutech silver head shell wires, Furutech interconnects and Furutech speaker cables (yes I like Furutech) and Raidho XT-3 speakers. Now on some albums the vocals are buried behind the music and you have a really hard time hearing the singer? Not all albums are voiced in this manner but enough that it is bothersome. I have a large dedicated man room (24 x 27) with minimum treatment. CDs sound just fine so I feel that it is with the phono preamp in the C-100? I have moved the speakers 100s of times and have them at 5' 8" apart and 8' 1" to the focal point and the soundstage is good and the vocals are better, but you still have to really listen hard to hear certain vocals on some albums. Most of my albums are 30 to 50 years old and have been cleaned with a sonic cleaner (best thing ever imho). Even some of my new heavy vinyl has this problem.
scooby2do
what phono input you're using MC or MM? In both cases it's loose-loose.
In case of MC the impedance is too low and MM the input is too low.
The solution is you should either have LOMC <.5mV or HIMM >4mV or outboard phonostage or replace load resistors of your MC input.

Check to make sure your cartridge is not connected out of phase. Red on red, green, on green, white on white and blue on blue.
First, why spend all that on gear and not on room treatment?  Try putting soft things on the floor between and around the speakers. That can clear up a lot of mid/treble clutter. This is a free tweak, try it with pillows and blankets before investing. Especially cover hard reflecting surfaces like the tops of entertainment center, sides, and a TV if any.

Second, toe in?
First of all you can use Cardas Test record to check phase and polarity of your system.