choosing input iron for receiving impedance balanced semipro gear ?

Hi guys, i would like to get some help for designing a nice coloured line amp, using synths and drummachines ( with pseudobalanced cables ), no mics around
mostly elektron gear which is impedance balanced .I don´t know what is the optimal load impedance for the machines, already wrote them but no reply yet..
really love this stuff but sound is a little grainy and edgy in the upper mids, very digital whith hard transients that are adding up not nicely in the mix, so i think some
slow opamp + iron config on some channels could help here.
that includes the input iron..
would like some api style amp after because i liked them over at the listening sessions on synth drums and because i can understand what is happening..
would like to hear about your favourite ( and yet get-able ) line  input trannys ( amps) maybe for different instruments on drums,synth bass ?
- thanks and greets
axel

Start with a 10K:10K isolation transformer - just about anything will drive that. There are plenty of makers of such transformers all with different 'sounds'.

Cheers

Ian