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
Never heard the Z Dac but have owned an iFi Stereo 50  & can attest to them making a highly musical DAC with a super low noise floor that can really dig detail out without being harsh.For $150.00 I doubt you will find many that compete & certainly none that better it..
Thanks for your response. All the reviews are good
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. 
That Topping DX3 looks like it checks a lot of boxes.  Do you have any idea how it compares for sound quality to the higher priced Topping DX7 Pro?

The Topping D90 looks like it would be amazing but it isn't a headphone amplifier.

I am really enjoying the sound from the FiiO BTR5 which is starting to seem like the best $100 I've spent.  I would love to find something with even better sound that is also a bluetooth/DAC/Amplifier that I can use for headphones and as an input to my integrated amplifier.  Ideal budget would be $200-500.
thanks for the posts. I will be looking into all the suggestions that were posted

Between the Dragonfly Cobalt and the Dragonfly Red, I thought the two definitely had a family resemblance in their sound. The Cobalt MIGHT have been a litter clearer, but not too different from the Red especially after adding a Jitterbug. I actually decided to get a Red over a Cobalt as it sounds more punchy which I think works well as I'm often listening on the go in different locations.

The real step up from a Dragonfly that I've heard is a Chord Mojo that provides greater 3 dimensionality and presence. You can get a used Dragonfly Red on eBay for about $140 to $150 shipped.