On Digital Cable it's 745 (SM16). It's the channels that often features different performers. I'm not sure if it's the same on Ignite (Edit: I tried looking for it there, but it seems the channels are different in the high 300s and low 400s.... and I didn't see it there, but I might have missed it)
It's also possible to stream these channels via the Stingray App on a tablet/phone, or via the Stingray music website on a computer browser.
I tried checking the holiday channels on legacy system, channel 745 (english) and 733 (french), the guide says they are holiday channels, but the song played are not holidays songs being played, I think someone forgot to switch playlist at Stingray.