Tweaking preamp and amp combination

I'm using SignalCorp.com interconnects, power cord for amp, and speaker bi-wire cables. The phono stage tubes in
the SP9 MKII are Electro-Harmonix 6922 Gold. The WX-2 cross-over filter that I'm using is set at 75K.
Thus at minimum an M5-HP (If I could find one) may make an improvement.

When listening to certain vinyl recordings I hear distortion in high timbre vocals and cymbals where playback is too bright which from my understanding may be due to the recording's improper mix or lack of proper compression.

In digging deeper to my original inquiry, can changes in interconnects, tubes, crossovers, cartridge or amplification compensate for playback of recordings to make them more listenable if they may have been mixed improperly?

charkune your last paragraph is exactly where I would start.The right nos tubes can make a huge positive difference.EH tubes have a clear 'modern' sound.Experiment with different brands that are known for a touch of warmth in the upper mids.
When you find 'the ones' that get you most of way there,then move on to try something else,maybe interconnects next.Room treatments are something to consider too.

Hi,
i had an SP-9MKII and i do not remember it sounding bright, quite the opposite and it had a very nice phono section. Neither is McCormack a bright sounding amp.
What kind of distortion? clipping? Is your cartridge correctly aligned? loading? You get this distortion from vinyl playback so you should start there.

Your problem is not your amp, and I find it very curious that when you say you’re having issues with vinyl playback you don’t bother to mention what analog gear you’re using.  Why???  Sheesh. 

I've owned the 3A Sigs and the SP9 MKII (and MKIII).  Neither caused any distortion on my vinyl.   What did cause the distortion you describe was bad cartridge setup, especially zenith.  
The Electro Harmonix tubes were ho-hum IMO.  In the MKII I liked Telefunken ECC88 but in the more detailed MarkIII I liked the E88CC.  
The 3A Sigs were sensitive to cables for sure.  I had cheap Monster Powerline 2 and going to Acoustic Zen Satori reduced glare dramatically.  Also, reducing "midrange glare" is a function of the tweeter control, not the midrange control, so a heads up on that.  Good Luck!