Tubes will help.
But setup it pretty important.
The Oracle mat is far more neutral than cork. What is important about the mat is that it should absorb vibration in the vinyl that results from the stylus tracking the groove. Turn the volume all the way down and play an LP- the more sound you can hear coming from the stylus itself, the less the mat is doing its job.
Arm height is important also. This is one way you adjust the rake angle of the stylus, which should be at the same angle as the cutter stylus was when it made the groove. This is about 92 degrees (but not exactly as the actual cutter angle varies from LP to LP as not all cutter styli are identical).
Some cartridges have the needle slightly off on the cantilever, making the correct rake angle difficult or impossible to achieve. This will result in sibilance and the like. So its a good idea to find out if your cartridge is alright first.
Many preamps are sensitive to RFI and ultrasonic noise, and this is generated by the cartridge when it plays. If your preamp has this problem, it may sound bright and the cure is loading the cartridge (so the loading is for the benefit of the unstable phono circuit, not the cartridge). The thing is, loading the cartridge causes it to be less compliant, so its to your advantage to work with a phono section for which loading is unimportant.
