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
No, because cd sound fine does not mean that all is in phase. You simple may have the cartridge pins connection on one side reversed. I would make sure this is correct. Double, triple check your cartridge connections. 

The connections on s should be as such

Red      White
Green   Blue

when looking from the front of the cartridge/table to the back.
scooby2do
the Pro-ject does use a mirror as part of the alignment process
But that's for azimuth, correct? Something like a WallyTractor uses a mirror to set tangency and actually aligns the cantilever itself.

I could be mistaken about the Pro-ject gauge, so I'd appreciate your clarification. 

I had this very same problem with my system after changing cartridges. After a week of pulling out my hair I found that the dip switches on my Jolida were set wrong. With the switches in the back they are hard to see and I missed 2 of the switches.
I reset the switches and everything returned to normal.
Wish you luck but I suspect that something in your phono stage isn't set to work with your cart.
Good luck
Greg
You also indicated that you have aftermarket leads in your head shell. They should be check to ensure you did not inadvertently connect the wrong.
Just to complete the list of suggestions, so that every possible nook and cranny of LP playing has been covered, try playing with VTA/SRA by raising or lowering the tonearm pivot a tiny bit.  But like I wrote up above, I really think you are hearing a characteristic that may be inherent to this particular cartridge, albeit you probably can change the soundstaging or tonal balance or whatever you want to call this problem at least a bit by making very small changes here and there.  Good luck.