I am interested in making my first full-size headphones/portable amp purchase

I can afford to buy: the Denon AH-D2000, the Sennheiser HD 650's, and 1 (and only one) portable amp or DAC/amp.

My two sources will be my 160GB iPod Classic (with an LOD), and my laptop with a 24/96 external sound card (Creative X-Fi Sound Blaster Express Card). I don't know if the sound card has a DAC at all, or if it does, whether it's good at all.

Basically, for the most part, the Denon's will be used with my ipod, and the Sennheiser's will be used with my laptop.

Since I can only afford to buy 1 amp, i've limited my choices down (based on price and features) to the Little-Dot MKI, and the iBasso D2 Boa.

I've read that the MKI has the best sound quality of any portable amp under $200. The main features that I look for are strong bass, a good soundstage, and definitely the capability of fully-powering 300 ohms headphones (Sennheiser HD 650).

My second choice is the iBasso D2 Boa. The advantages of this amp is that it has a built in USB-DAC. But since it clearly (or at least from what I've heard) doesn't have as good sound quality as the MKI, and i can only use the DAC with my laptop, and not my iPod, I feel like (regardless of the price difference - that's not the issue) i would benefit from the MKI more.

But I really don't know. Do I need a DAC? Does my sound card have one? (Can someone check it - i looked on the tech specs and couldn't find it)

Should I just stick with the Little-Dot MKI, and not bother with the DAC? It's all so confusing!

Also, I ask this in every thread, but no one seems to answer it - but why oh why are these interconnect cables so expensive?? I've seen them for upwards of $150! For a 4 inch mini-to mini (or ipod dock-to-mini) cable? Is this one ok? (IPOD LINE OUT DOCK WITH CABLE & PLUG (BLACK COLOR) - eBay (item 300255460077 end time Sep-09-08 18:09:06 PDT))
and can I get them any cheaper? What features do the $100 ones have over the $2 rubber cables from radioshack? Can anyone explain the audio quality difference?

And then please help me out with the amps. And whether these are good headphone choices for my "situation". Should I switch the Senn's with the Beyer's? (regardless of price - i just want quality, and I found them all for less than $300) Another one of my necessities is comfort, and the Denon's and Senn's both seem to have a lot of padding, so that seems good. The Grado's (SR325i) do not look comfortable at all. For the portable pair, I think the Denon's are good, but for the at-home pair, I'm leaning towards the Senn's, but I'm still considering the Beyer's (990 Pro or 2005)

Thanks alot

All sound cards contains DAC.

Top end Beyer, Senns, AKG and etc are quality headphones, which to get depends greatly on your taste. However you'd be struggling to find a portable that would drive them well. That said the Mk1 is among the most powerful portable I've heard.

Boa is not necessarily worse sounding than Mk1, but it definitely have less power and warmer sounding than the Mk1. But Boa is smaller, lighter, has DAC and better battery life. You can swap opamp with the Mk1 to customise the sound, but not with Boa.

Whether expensive cable is worth it, it depends on whether you are a believer or not. Some could tell the difference, while others not.

It looks like you'd benefit with a DAC too.