Most of the MSOs/LCOs are still push SD packs for cheaper bills, so cable customer compromise quality in their 4K tv. but IPtv is costlier than Digital cable or DTH due to fiber/airfiber service (Rs.800+), so definitely iptv quality will be good over digital cable & DTH bcoz of huge bandwidth of internet.
They stopped access now. But they provided compressed stream in iptv earlier. Didn't check recently. Airtel is best in terms of audio quality as compared with other dth providers.