Yes, that was covered early-on in this thread.I'm about to give this mod a shot, when wiring it all back up there were 2 additional leads from the speaker RCA inputs that connected to the OEM amp. I'm assuming this is what you meant by losing the ability to power through just the speaker line inputs? So my configuration would have to be speaker line inputs plus LFE?
I almost took that route myself (replacing the amps in the BP7006 units). But I got mired in all the options - everything from a 'boxed' external amp (like the Fosi), to the many "amp boards" available on eBay and Amazon. I wanted to retain speaker level inputs, so that limited my options. If I built it myself (using an "amp board"), I could retain speaker level inputs by adding a "Line Output Converter" (capable of about 40 watts of input power) for about $10-20 each on eBay, Amazon, or Parts Express. I also wanted the ability to adjust the volume level and the cutoff frequency. Some of the cheap / low power Amp Boards included those features, but the better, more-powerful amp boards did not ... so I'd need a separate subwoofer preamp board (available on Amazon for under $10, though I didn't find too many options to choose from). Powering the amp board was another big question. Some include their own power supply on the board (e.g. ICEPower), but they're big and expensive (over $100 each) and they still needed a separate preamp and LOC. Cheaper amp boards required a separate power supply, and I thought I'd reuse the original toroidal transformer from the Def Tech amps - which produces both 24VAC and 49VAC. But not all Amp Boards accept AC voltage, so I thought I might build my own bridge rectifier / filter cap circuit using a PCB kit easily found on eBay specifically for that purpose (another $10 or so). Of course, I'd need to mount everything on the original subwoofer amp backing plate, not knowing what kind of hurdles I might hit trying to mount everything. Still, it all sounded doable, but the cost would still probably be $100 per speaker ... AND a LOT of work!
In my case, I was able to repair my original DT amps (hope they stay fixed). But if I replaced them, I think I'd buy standalone / boxed / external amp(s) like the $49 Fosi subwoofer amp (and one LOC) per speaker. I have a Fosi amp (small stereo amp with subwoofer output) which powered the DT subwoofer driver fairly well (moderate listening levels). And I could adjust the cutoff frequency and relative volume. And an external amp could be redeployed on another subwoofer in the future. Anyway, these were the many thoughts that went into this project. Hope it helps.
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