Although a lot of equipment having balanced outputs can tolerate having the inverted signal (pin 3 per the convention used in the USA and many other countries) grounded, some can't (see this thread for example, although it involved a solid state component), and personally it strikes me as being being poor practice at best. Also, the output impedances of the Einstein preamps are very low (especially for tube designs), which everything else being equal increases the likelihood of there being a problem.
There are three approaches that occur to me:
1)Cardas can supply adapters which leave pin 3 unconnected, although they are significantly more costly than standard adapters.
2)You could have a cable supplier custom make an adapter cable which leaves pin 3 unconnected.
3)You could purchase a Jensen transformer, such as their model PI2-XR (which is the same as the illustrated model PI2-XX except with RCA output connectors), and an additional set of cables if necessary. It would connect to the amp input with a very short length of RCA cable, and to the preamp with whatever length of XLR cable is necessary.
A transformer such as that one would in effect convert the unbalanced input of the amp to a balanced input, with the advantages that can potentially provide. Those would include reduced susceptibility to ground loop issues; reduced sensitivity to cable differences, especially in combination with the low output impedance and excellent drive capability of your preamp; perhaps lower noise levels, etc. A number of users here whom I consider to be highly credible and have very high quality systems have reported excellent results using Jensen transformers to adapt balanced to unbalanced connections, or vice versa, although there are also one or more highly credible members who assert that they introduce subtle sonic compromises.
Good luck. Regards,
-- Al
There are three approaches that occur to me:
1)Cardas can supply adapters which leave pin 3 unconnected, although they are significantly more costly than standard adapters.
2)You could have a cable supplier custom make an adapter cable which leaves pin 3 unconnected.
3)You could purchase a Jensen transformer, such as their model PI2-XR (which is the same as the illustrated model PI2-XX except with RCA output connectors), and an additional set of cables if necessary. It would connect to the amp input with a very short length of RCA cable, and to the preamp with whatever length of XLR cable is necessary.
A transformer such as that one would in effect convert the unbalanced input of the amp to a balanced input, with the advantages that can potentially provide. Those would include reduced susceptibility to ground loop issues; reduced sensitivity to cable differences, especially in combination with the low output impedance and excellent drive capability of your preamp; perhaps lower noise levels, etc. A number of users here whom I consider to be highly credible and have very high quality systems have reported excellent results using Jensen transformers to adapt balanced to unbalanced connections, or vice versa, although there are also one or more highly credible members who assert that they introduce subtle sonic compromises.
Good luck. Regards,
-- Al