What Are Good Upgrade Tubes For a Jolida 1501RC?

I am expecting my Jolida 1501RC any day now. I have a pair of Sovtek 12AX7LPS tubes I could replace the stock tubes with. Are there any other new tubes that go well with this amp? I am driving a pair of MMGs.
Jim; I'm trying out 12ax7 tubes today on my Almarro A205A MkII integrated amp and found the Electro Harmonix 12ax7EH seems to follow the same characteristics as their 6922. This tube tips up a bit from mid-range on up which is a bit too hot for me but may fit your Jolida needs. The best all-in-one information source on 12ax7 is still "Joe's Tube Lore" posted on the audioasylum.com site. Let us know what finally works for you (and what didn't). ..... Mike
I believe I had NOS JAN Philips in mine when I owned it that were a very nice improvement over stock.