Parasound C1 and C2 controllers both offer two programmable channels that may be programmed as non-summed L and R sub outs. These have the balanced connections you are seeking (although auxillary channels are unbalanced outputs) and very good audio quality, but no Audyssey XT. The C2 controllers owner manual states the following regarding programming Auxiliary Channels 9 and 10
"Each of these two channels has independently adjustable high-pass and low-pass filters and provision for deriving content from any or all of the other eight channels, mixed in any proportion you like. Filter type can be None, Lowpass, or Highpass. Filter freq can be set in 5-Hz increments. The high-pass filter, commonly used to keep bass out of small speakers, can be set from 20 Hz to 1 kHz. The low-pass can be set from 20 Hz to 18 kHz. Mix Level sets the percentage and polarity (phase) of the new channels content that comes from each of the other 7.1 channels, in 1% increments."
The Parasound controllers were recently discontinued and are available at substantial discounts.
"Each of these two channels has independently adjustable high-pass and low-pass filters and provision for deriving content from any or all of the other eight channels, mixed in any proportion you like. Filter type can be None, Lowpass, or Highpass. Filter freq can be set in 5-Hz increments. The high-pass filter, commonly used to keep bass out of small speakers, can be set from 20 Hz to 1 kHz. The low-pass can be set from 20 Hz to 18 kHz. Mix Level sets the percentage and polarity (phase) of the new channels content that comes from each of the other 7.1 channels, in 1% increments."
The Parasound controllers were recently discontinued and are available at substantial discounts.