Beyerdynamic BV37590 any info on this transformer .. its input of a card from 1978 that I also dont know much about a DTL SDA-1-10 ??? line or pre amps I spose I have 8 in a rack 7 of 8 have BV 371 001 081 transformers in I believe they 1:1 ratio..I was wondering what I could use them for ? thanks.