Where is the problem? Tracking error?

Good listening and observational skills. I've heard exactly what you described.

First, I agree about the Mint. It's about the best $110 you can spend on a vinyl front end. Just be aware that each one is custom made for a specific tonearm. If you change tonearms you'll need a new one.

Also agee with Dan on optimizing every aspect of your setup. VTF, VTA/SRA, azimuth, anti-skating (if you use), levelling of table, isolation of table, etc., etc. Each of these will impact the sound.

Some bad news: every component in your vinyl front end is contributing to that compression: Ace, Scout, JMW and almost certainly your phono stage. Phono stages are extremely vulnerable in this area. I can count on the fingers of one hand the phono stages I've heard that don't compress as you described.

Where to start? After levelling the table and aligning the cartridge, work on fine-tuning VTF next. The music will tell you if you're moving in the right direction - only practice and thought can connect the dots between what you're doing and what you're hearing. Just get in there and mess around.

Classical music provides the severest test of a playback system. I've heard dozens of systems that reproduce rock, blues, singer-songwriter or even jazz acceptably. OTOH, I've heard only three systems that reproduced a wide range of classical music acceptably. Only three, and only one that I could begin to live with (and do). Many systems fail so horribly with classical that my partner and I are driven from the room. You've taken on audio's toughest challenge. To whatever extent you succeed, you'll learn more than other genres can teach you.

BTW, an orchestra of authentic instruments, chorus and vocalists is even tougher than a modern orchestra. That acid test will shame most any system. Our current system has only begun to pass this test of tests. We've never even tried our toughest LP's in other systems, they would sound too wretched.

A difficult realization for many audiophiles is learning that they must wean themselves from any desire for "musicality" in their components. There is no such thing as a "musical" playback component. Musicality comes from musicians. If the recording is good, the job of a playback component must be to reproduce what's on that recording, neither more nor less. If the recording is bad, there's no point trying to compensate in the playback system because there are an infinite number of ways a recording can be bad. There's only one way a recording can be good, so embrace neutrality in your heart as well as your head and you can make real progress. Settle for the artifice of musicality and you never will.

Agree that tonearm and platter both have a huge influence, though not necessarily on tracking error. If you've aligned the cartridge well with a Mint then you've minimized overall tracking error distortion about as much as possible without going to a longer or linear tracking arm. The compression you're still hearing is mostly not caused by tracking error.

What a tonearm and platter do influence is the stray energies coming from the stylus-vinyl interface. These, if allowed to reflect back into the cartridge, muddy the signal and contribute to that compression you described.

Acrylic is not the best performing material in this respect, so you might consider messing around with platter mats. Check the forums for what others have tried with a Scout. I'm not sure what works best, or indeed if any mat is desirable with a Scout. Going the opposite direction, you could try a center clamp and/or VPI's periphery ring clamp. Both improve exactly this area of sonics on my table, but of course every platter reacts differently.

Does your JMW allow for damping fluid in the bearing well? I know some versions do. Unipivots often benefit from this so experimentation may prove enlightening. Be aware that TINY changes in the amount of fluid can have an audible impact. Finding exactly the right amount for any given cartridge requires careful experimentation. (By "tiny" I mean the smallest amount you can add/remove using the point of a pin. Yes, it's nuts...)

Many owners of Scout family tables report good results from the Cloud Nine isolation platform, and/or from replacing the stock spikes with better ones from Star Sound, Mapleshade or Walker. Every reduction you can make in spurious energies reaching the cartridge will help.

Good additional insights by Stringreen.

>> I suspect that bias compensation acts like damping...

Exactly so, as does VTF, and for identical reasons. Both apply a constant force (whether lateral or vertical) which presses the cantilever into the suspension. Pressing a vibrating rod into an elastomer dampens the vibrations. The precise effects will vary by frequency, amplitude and the characteristics of the particular elastomer and rod.

As Stringreen observed, every cartridge's sweet spot for VTF is unique. (The same is true for anti-bias, though the differences are subtler.) The only way to find it is by experimenting. I'd suggested starting with VTF because its effects are the most audible, at least in my setup. I adjust much more frequently than he does, sometimes daily, but for exactly the reasons he described.