Each phono is different but being limited to 100 ohms input might be er...limiting 
( btw the Phonolab offers 68db gain at 27 ohms output by rca &/or xlr or 74db at 100 ohms xlr ( which is the same output inpedance as the Boulder...)

( btw the Phonolab offers 68db gain at 27 ohms output by rca &/or xlr or 74db at 100 ohms xlr ( which is the same output inpedance as the Boulder...)