Your Air Tight PC-1 has an output of .6mV with an internal impedance of 2.5 ohms, according the cartridge database. The problem is that it is a relatively high output voltage compared to the internal impedance. It depends on the overload voltage on your phono preamp as to how high you can boost the signal. Most phono stages overload at about 10 mV. So doing the math 10/0.6 = 1:17 is the highest step up ratio you can use. You can readily find 1:16 step ups, but they will give you a reflected impedance of 184 ohms. It should work fine, since the recommended loaded impedance is greater than 25 ohms. Impedance matching is not critical for SUTs, as long as the impedance load is not too low. Too high is ok. Some may recommend loading with resistors to make up the difference between the 184 ohms and the 25 ohms, but I personally find it is not necessary.