PMC is transmission line. ATC is sealed box.
They are both top quality monitors many record companies use. I would say if you have a big listening area, stick with the PMC's larger models. The ATC are more for a medium to small area. PMC is also cheap and require less power for full performance. I have seen sucessful good sounding systems with both. ATC has a more powerful sound, never fatigue. PMC has a very true, life-like sonical signature, better soundstage than the ATC. However, I heard them in different set ups.
They are both top quality monitors many record companies use. I would say if you have a big listening area, stick with the PMC's larger models. The ATC are more for a medium to small area. PMC is also cheap and require less power for full performance. I have seen sucessful good sounding systems with both. ATC has a more powerful sound, never fatigue. PMC has a very true, life-like sonical signature, better soundstage than the ATC. However, I heard them in different set ups.