A bit of a slippery slope here. Tubes really do make a difference, but as with everything, it's relative to parts quality supporting it all. I spent a considerable sum on 300B tubes plus the others for my Manley preamp and it changed considerably for the better.
The Manley came stock with decent tubes, EH. My Mahi Mahi mono blocks came with EH stock. Upgrading those really changed and improved performance. I don't know the level of your integrated. Millercarbon is perhaps correct that the other pieces are more important.
