Tube Amp Questions

Hello all!

I've decided to build my system around my Thiel CS 3.7 speakers. Currently, I'm using an ARC LS-7 tube line-stage (purchased just 3 weeks ago) feeding my old Denon PMA-2000 IVR integrated. Sources are laptop running Tidal & Roon, as well as Denon 2900 CD/SACD player.  Musical tastes are varied, but I listen mostly to classic rock, the blues, classic jazz & Latin/bossanova. 

My questions are regarding tube amps. One, in real-world experience, are they really that labor intensive to maintain & operate?  Two, the particular amp im considering is an ARC VS110. According to ARC, it draws 400 watts at idle, 620 at rated output & 900 maximum. How big of an impact does running an amp like this have on an electric bill? 

These are newbie questions, I know, but after a really long time as an admirer of the "High-End", I've finally decided to leave "Mid-Fi" behind, albeit by going the vintage/pre-owned route. 

Thanks for any input or reccomendations!

Arvin