What the *#$@ happened??

I'll keep this short, just hoping someone can let me know what's going on. I changed out the platform my TT was on to a much denser wood, and I'm not really happy with the results. The good, I can hear more detail in the music, subtle nuances are more prevalent, better instrument separation, especially in complex arrangements. The bad, the whole stage moved back and got flatter, it lost depth. And the 3 dimensional characteristics of the singers voice also lost luster, became flatter as it were. It almost seems like I'm listening to a stereo now instead of a live performance. I thought the heavier wood would improve the sound, not degrade it. 
Anyone know why this happened?
"Technically Symposium is better than wood."

Technically it's better than peanut butter, too.  Or say a can of Spam.
Hi Shawn,  Are you judging based on aural experience or based on sound reproduction?  You stated that with the new plinth you "hear more detail in the music, subtle nuances are more prevalent, better instrument separation, especially in complex arrangements."  That does not happen by a miracle.

The stylus must track the record groove more precisely to retrieve this sound information.  The stylus cannot selectively track the more complex passages and fail at the simpler undulations.

I suspect that you are listening to studio recordings rather than live recordings of acoustic instruments and voices.  Studio music sounds flat when heard as originally recorded.  Conversely, acoustic instruments have timber and when recorded in a hall (like classical music), they have an ambient sound.  Nothing is added artificially, like reverberation in studio-recorded music.

Before your new plinth, you believed your listening experience was like hearing a "live" performance.  But what you really were hearing is echo of the energy from the stylus tracing the groove and the energy resonating back into the stylus rather than being absorbed in the massive plinth.  Thus, it gave it a fuller sound, yet with less sonic detail, as you stated.

I suggest you listen to your new plinth for a while and experience what you have been missing.
Maple is the most popular, I never heard anyone use ebony or ironwood, as an example.
My plinth, platter and armboard are made of cocobolo, which is denser than ebony and similar in density to ironwood. The plinth and platter are also loaded with multiple chambers of lead shot. The maker (sadly, no longer in the TT business) experimented with and sold TT’s made from many hardwoods, including ebony, over the course of a 5 year development project. His findings were generally that, the denser the wood, the better the sonics... for the reasons Larryi explained. I heard several iterations, owned three, and completely agree with those findings.

Maple was tried early in the development and quickly discarded as less than satisfactory when compared to denser (though admittedly more costly) options.

Larryi’s post was astute. Listen closely and try to distinguish between sound that you "like" vs. sound that is more revealing of the actual performance as recorded in the grooves. On a sufficiently revealing rig, the artificial aspects of studio recordings become apparent. A good TT reproduces the truth, whether we like it or not, and it sounds like your tweak may have gotten you a step closer.
Thanks for all the info gentlemen, I appreciate it. And thanks for the detailed explanations redglobe and dougdeacon. I'm going to leave things as they are for now, and spend some more time listening to a variety of recordings that I'm familiar with. I have a feeling that you guys hit the nail on the head.

While I certainly appreciate the length of the explanation of various woods, I d respectfully like to disagree strongly on the underlying premise - that density of the wood is what’s important for the sound. In fact the better sounding woods such as Mpingo wood, maple and spruce, to name a few, are not particularly dense. I could post the table of wood densities but I’ll leave that for the student. It might have been I who mentioned ironwood as I often use that wood as an example of a very dense wood that doesn't do much for the sound, as a form of irony.  Get it?  Of course ebony has a wide usage in musical instruments as well as Mpingo discs and other audiophile products. I used to have an ebony turntable clamp product myself way back when.