Well, sorta... When I built my most recent layout (and probably my last), I intended to go strictly with DC, as I have about 50 diesel and steam locomotives in HO, which are all DC. But my bride of 45 years bought me a Proto2000 F7AB set which happened to have DCC and sound. While it will run on DC, I liked the idea of hearing the horn blowing. So I picked up an MRC Tech 6, 6.0, which will handle both DC locos and DCC with sound. However, I have some diesels that look just like the Proto2000 units (C.B.&Q. freight), and I didn't want to chance messing up a DC motor with the AC. So I acquired an MRC Tech IV 206, and wired a DPDT switch on my control panel so I keep the Tech 6 on DCC and use the Tech IV for DC locos. Since I am a one-man operation, and my layout fills a 14' x 14' room with a folded dogbone, peninsula arangement in a reverse 'G'. with a real spagetti bowl track layout, I can park the DCC trains and run a DC or visa versa. I have and will probably acquire a few more DCC with sound (Athearn is set to bring out an F3A,B painted in "Q" passenger scheme for the California Zephyr), there is no way I will convert most of my DC equipment. Too much money, and would take too much time. And, yes, the DC equipment runs quietly, and smoothly (especially my kitbashed Mantua steamers with Canon coreless motors, gear boxes, etc.). Of course, when friends come over (especially kids) they like to hear the sound...