Sirspeedy, Once the stereo LP was introduced, everybody began using the same EQ curve, which was defined by the RIAA. That curve was nearly the standard in the mono LP era with very little exception. It was during the 78 period that every label had their own EQ curve. Older tube preamps like the HK Citation 1, Marantz model 1 and the like had EQ switches for these curves.
There were a number of manufacturers of stereo LP matering electronics, for example we have the Westerx 3D cutting system outfitted on a Skully lathe. The limiter module allows you to create high frequency reduction through a series of switches. These are often reserved for master tapes wherein the mastering engineer is allowed to exercise some judgment. In addition, every LP mastering system has a 'signature' sound relating to the mastering head and the sonic character of the electronics.
But they all are based on the same EQ. Changing the EQ to taste or the like has some advantage with LPs that are poorly recorded (in this case the majority of DG classical would be a great example). For me this is very much like the CD problem: if I want the music, and its only on CD, I deal with the CD colorations because I want the music. Dealing with poorly mastered LPs is the same thing.
In a nutshell, IOW, a properly mastered LP, regardless of country of origin or label will sound its best with the standard RIAA curve. If not, there is a problem in the recording process.
Establishing a proper reference in this area is a hefty problem; one that we had to face down before we were able to make any significant progress, one that every high end audio manufacturer faces whether they know it or not, and one that every record label faces whether they know it or not (and a lot of them don't!).
One thing that I can tell you about that process is that to get to a real reference, you **have** to remove any sources of coloration that will obscure the recording. To us that meant transformers, interconnect cables, and other compromises in the signal path, like Class A vs Class B. Having gotten to a point where these sources of coloration are minimized it becomes very easy to hear what something like even a decent SUT does to the sound. That puts us back on-topic right? :)
