I don’t think you’re going to find a wideband that has a sensitivity near the SB29RDNC (94 dB). It’s just a trade off of being a wideband. If you want loud I don’t think a wideband will be a good choice (they will be far less likely to keep up with the mb8). I’d probably listen to what Eric recommends. He obviously knows his speakers very well and will likely give you the best advice on what will sound best for them.
I’ve had that tweeter (Sb29rdnc) and it’s a great tweeter. I’ve had many widebands as well and any 2” wideband will fit in almost the exact same space as the SB29RDNC.
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