I agree with playing with speaker positioning first. Closer to the walls should get more bass (tighter?). Keep in mind that this is a very "mellow" system. Quite nice, clean and detailed, but won't have a lot of bite.
As far as the tubes for future reference: 6922s should last 5000 to 10,000 hours. Big reason why manufacturers love them. Changing tubes will make a huge difference. Let us know what kind you have now and someone should make a good suggestion (don't say sovtek, please...). When the tubes start to go, everything will get muddy sounding when you push them hard and the whole system will lack power. They are easy to check and I'm sure you can find someone near you with a tester.
As far as the tubes for future reference: 6922s should last 5000 to 10,000 hours. Big reason why manufacturers love them. Changing tubes will make a huge difference. Let us know what kind you have now and someone should make a good suggestion (don't say sovtek, please...). When the tubes start to go, everything will get muddy sounding when you push them hard and the whole system will lack power. They are easy to check and I'm sure you can find someone near you with a tester.