change pre-amp/amp freqencies for buttkicker LFE minis

Hi,

Note: also posted in head-fi but no response.

I wasn't sure about which section to post this in here, so apologies if I've got it wrong.

I have two Buttkicker LFE minis screwed into the frame of my sofa. The sofa is on rubber mats.
The Yamaha RX-V477 LFE output goes into a Y-splitter, one leg going to a Dali E12F sub, the other into another Y splitter connected to the RCA inputs of a Fosi P1 preamp. I've replaced the tubes with 5654W tubes.
The RCA outputs go into an Aiyima A07 amp, with which I'm using a 32A 5V power supply. I have a 48V supply but don't use it because the fan is noisy and it doesn't seem to make much difference.
The speaker outputs of the A07 are connected to about 7m of 2.5mm2 copper speaker cable.

The buttkickers rattle a bit at lower frequencies, a problem that wasn't solved with the rubber feet on the sofa. I have the crossover on the AV receiver set to 120Hz so that the Dali sub can handle lower frequencies, but this also means that I get eg male voices through the buttkickers, which I do not want. Obviously I can buy a crossover and connect the LFE output to it and only send higher low frequencies to the sub and lower low frequencies to the buttkickers, but I'd like to try and do something with the pre-amp and amp, and in any case I still want the main sub to handle the lower low frequencies.

The buttkickers are sensitive down to 10Hz, but the pre-amp and amp only pass a minimum of 20Hz. The pre-amp has bass and treble tone controls, and obviously I have bass on max and treble on mimimum.

I would like to modify pre-amp and amp to pass signals down to 10Hz and nothing above something like 100Hz, and also modify the pre-amp tone controls to amplify a much lower frequency range so the bass knob controls something like 10-40Hz and the treble 40-80Hz. My (somewhat limited) understanding of electronics leads me to believe that I can replace a few capacitors to achieve some - if not all - of my aims.

I'd be grateful for any thoughts, even "you should have read the FAQ, it's all there", "why on earth are you using a valve pre-amp for low frequency transducers?" or "no, not possible, too complicated to juggle caps and resistors". I'm capable of using a soldering iron.

Pics are from the pre-amp (which has tubes, hence the hesitation about which section to post this in).

Thanks!
 

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Thanks for the reply. No output transformers. The op-amps are predictably NE5532P, although I don't know if they are genuine. The treble/bass potentiometers are identical and I'm wondering if they'd be something I could swap out.
 

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