So what could be the best bang for the buck?

All of them except the NAD, are at the same exact price point of 400€

-I want this for regular listening/enjoyment, but also for checking my mixes/compositions..

I'm not so interested in power/wattage...

Rather i'm more into overall sound quality, frequency response, THD, quality of inputs/outputs, heaphone out (very important) and DACs (if any)....

Of course I want a natural, transparent, flat, sincere sounding amplifyer.. I dont want anything hyped or scooped, or with too much "trademark" sound, if you know what i mean..

With it I will use regular hi-fi speakers, aswell as whatever best passive monitors i can find.. (they seem hard to find, so suggestions are welcome too)

(I already got proper active monitors with a pair of EVE SC208..)

I will be using some Beyer DT880 Pro 250Ohm headphones, as well as some regular Pionner, and the audio interface is for now an MAudio Delta 1010

So what do you all think?

Thank you.

PS:

Regarding heaphone-out quality... could it be wise to get this thing called the "Can Opener" and just run it from the main outs?

http://www.vinylflat.com/canopener.html

Is there any similar product made by any reputable company that you know of?

PS": Here's some links
Denon - http://www.denon.co.uk/uk/product/pages/product-detail.aspx?catid=hificomponents&subid=amplifiers&productid=pma720ae

Rotel - http://www.rotel.com/UK/products/ProductDetails.htm?Id=503

Marantz - http://www.marantz.es/es/products/pages/productdetails.aspx?catid=hifi&subcatid=amplifier&productid=pm5004

NAD - http://nadelectronics.com/products/hifi-amplifiers/C-326BEE-Stereo-Integrated-Amplifier