I would suggest a single Altec 605 in OB or vented cabl like 612 or 620 (604's too!). The 605's if I am not mistaken is a combo of 515 and 802 mated together while the 604's are 416 and 806, which are two of the best driver's Altec ever produced. At around 100+ dB, you will not have a problem looking for amps to drive it to its full potential.
I run 604's in OB, or a 414 with 802D in OB for mono once in a while and I really enjoy how it sound. Use the old RCA phono circuit design (RIAA) with single ended amp (SET or Pentode strapped as triode)and you are set. I prefer using a mono cart like the Denon 102 and I avoid stereo cart converted to mono and stereo preamp switched to mono by combining the two channels. Enjoy!
I run 604's in OB, or a 414 with 802D in OB for mono once in a while and I really enjoy how it sound. Use the old RCA phono circuit design (RIAA) with single ended amp (SET or Pentode strapped as triode)and you are set. I prefer using a mono cart like the Denon 102 and I avoid stereo cart converted to mono and stereo preamp switched to mono by combining the two channels. Enjoy!