To integrate one of your tube preamps' phono stages with your pre/pro, run your turntable into that tube preamp's phono inputs, with its input selector (or record selector if it has one) left set to phono, and then take the "TAPE OUT" outputs (also known as "REC OUT" or "LINE OUT" outputs) into an unused stereo line input on your pre/pro (NOT the phono input, if it has one). The tube preamp will be providing pre-preamplification and phono equalization, but its volume control and output amplification stage will be bypassed, effectively turning it into a phonostage. (Keep in mind that in order for the tubed unit to operate properly, you will still have to keep it outfitted with good correct tubes in all the tube sockets ; it's not OK to just remove the line-stage gain and output buffer tubes from the circuit, even though you won't actually be using them to drive an amplifier.)