Thankyou David for your response. I had noticed on the net that people seem to uise the K series amp for low bass, such as driving subwoofers, which seemed to be at odds with my experience as you imply. Please note that i am entirely happy with output level of most of the bass range, just not the lower bass such as less than 30hz odd.
The manual for my preamp cites the following specs: Sensitivity (for 1v RMS output) = Line 220mv; Analogue input impedance= 10k; output impedance (all analogue outputs)=50R; Maximum output voltage =10V rms 20Hz-20khz. The manual for my other power amp that is designed as a sister to the preamp has specs: Input Sensitivity=1000mv; and Input Impedance=31KOhm.
One thing to note is that I only have a single RCA for each channel from preamp and because I am bi-amping, I purchased a 'splitter' which is like a double adapter--I plug a single RCA into preamp left channel and it splits the signal into two lines, one that I plug into a power amp channel to be used for top end and the other into a different power amp channel for bottom end. I added an adapter to this male RCA so it would fit in K@2 socket. Does this splitting have an impact on impedance?
Because power amp says Input sensitivity=1000mv, I set switch on K2 to 0.775v and adjusted gain back until overall bass level for most bass (ie 30hz and up) seemed about right. However, the lower bass was not very prominent and if I adjust gain to max, the mid-bass is too much and low bass still too little. This is in comparison to other respectable power amps I have tried.
I have had a look at the wiring docco you send and need to read it again as I dont really understand how to suss if i have the balanced thing wrong--no reference to this in manuals of my current amps. Any further advice would be greatly appreciated.