Looking for headphone amp/DAC


I am using Sony MDR-7506 headphones with my Apple iMac. I don't want to spend more than $150. I spend a lot of hours at my computer listening to music. I mostly listen to Hi Rez Qobuz. I am thinking of the the Zen Dac. Any thoughts about this
galleybob
I prefer my Audioquest DragonFly Black (with Jitterbug) before my iFi nano. If you can go up in price the DragonFly Red is probably even better.
I use the Dragonfly Red and am very happy with it.  I tried the Jitterbug with it and transparency and soundstage were both negatively affected so i just use the Red on its own.  FWIW. 
I’ve got those Sony MDR 7506, I think they might be the brightest sounding headphones that ever were.   Brighter than my Grados even.  You are going to need to carefully select the amp for those phones. I’d suggest something that has a warm sound signature.  
 And just so you can get a different flavor, I suggest getting a pair of Koss Porta Pro headphones.  A warm sound but still good detail.  Don’t be thrown by the looks, they’ve been in production since 1984 for a reason.  At 30 bucks or so, you’ll thank me.
Thanks for all the responses. I am trying to decide between the Ifi ZenDac and Audioquest Cobalt. The Cobalts are a lot more money so I am reading the reviews
I’d add the Topping DX3 Pro v2 to your list that can be had at Drop for $209.  Best of luck.