Oops.... I thought I remembered from another thread that you had a BG-250 combo. Well anyway, you've got half the pieces to the puzzle.
I modified the input connector dish to have a couple of Speakon NL4 connectors in parallel to the quarter-phone inputs. Here's a pic of the result, but I not particularly proud of the job. It ain't especially pretty, but it'll work. I've fabricated countless input panels in aluminum or steel, but this may have been my first one made out of ABS plastic.
I like the cab well enough -- I agree that it might sound a little boxy, but it's EQ-able. I'm with @InkCow in that I'm a bit more tolerant of the sound because of the form factor and the price. I went ahead and put two Speakons on it, in anticipation of adding a second cab, but I'm not sure I'll get one -- I don't really need two cabs for the purposes I bought this for. I might just get a second one because they're so cheap; at some point they'll probably be discontinued or updated and then no longer available.
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