Low Cost DACs


Currently I have my laptop connected directly via 1/8 jack from headphone outlet into 2 RCAs directly into my tube amp. Quality of sound is lacking to say the least!
I am considering adding an inexpensive DAC ( iFi AUDIO nano iDSD LE Portable DAC  or iFi Audio nano iOne DAC ) into the stream between the laptop & amp.My question is: will this influence the overall sound I'll hear out of my speakers? Will adding such a DAC help to increase the quality of sound produced by the system?
I'm not interested in spending a lot of money on a DAC as this is a source that I don't use as much as some others already in the system.
wcc10
I’ve got a Meridian Director selling for $400.  It was a large difference from my built in DAC in my receiver. It’s amazing what a good DA converter can make the music sound like. 
I have a Micromega MyDAC for my desktop, and it is very good value for the money. Can't compare to Schiit as I haven't heard any of their gear. The Cambridge DacMagic sounds warmish compared to the MyDAC which is about neutral. 
Yes, for what the MyDAC goes for used it is hard to beat. Linear power supply, USB, optical, coax inputs.  The Modi3 represents great value at it's cost new. 

That said, the use of a of a USB driven Modi2 which can be purchased used for~$50 would make for a real improvement over computer analog output.
I appreciate & respect anyone who takes the time to research audio components to the point of comparing graphs of actual signals, harmonics, etc..Despite my hearing not being what it was before many Rock concerts & loud motorcycles, I still rely on what I hear out of my speakers. No doubt, you could show me why one component is "way" better than the next. And I would believe you. But still, my ears are the ultimate judge and I trust them the most. Certainly this has resulted in much trial & error and more than one component for sale here or on eBay. My point; sometime it's easy to be unduly influenced by the latest stats or any "expert" review on the ultimate audio magazine.