Sheffield definitely does have an amazing underground dance scene, even starting with the student union, we have the internationally renowned tuesday club who've had so many amazing underground artists every week, Jamie xx, Ivy club, shadow child, bondax, the list goes on. If you're into drum and bass they also host hospitality twice a year.
Then hope works and night kitchen are both really cool venues set in the more industrial part of the city and they offer all the house and techno.
Tank is an underground (literally) club open 11-7am playing house type music.
Arch9 and Yellow arch studio is another venue that's little known about to students if you're not in the scene.
Theres a lot of underground pop up club nights as well in some of sheffields steal foundries and the abandoned Woolworths.
Every couple of years there's also peace in the park, a free festival (originally started as a protest of invading Iraq) with the biggest bass system you've seen in a while, followed by the illusive peace in the dark rave.
Basically I think Sheffield is an awesome place for underground dance music, and it only gets bigger and better the further you get into the scene.