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
Cambridge DacMagic for 75 is a great little unit.  Personally, instead of using a laptop with pandora I have found that using my cell with Tidal gets much better quality sound and I can download as much as I want to my phone.  And you can take the phone and dac with you anywhere.
The only problem I have with Tidal is the $20.00 per month fee. Call me "cheap" but that seems a bit high. I did try it for free for a while and agree, it’s a better option than Pandora in terms of music quality..
I have a Schiit Modi2 and also purchased a used Micromega MyDac for $125.  Either would make an improvement when playing from a computer. The Modi 2 can be found used for close to $50. That version has USB input only however may be all you need. I use mine to stream spotify from my Macbook pro. The MyDac has USB, optical and coax inputs. 
I've pretty much made up my mind to go with the Schiit. Only question, is the Modi "Multibit" $100.00 better than the Modi 3?Yes, agree a USB input is all I would need at this point.