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 like the prospect of "analog sounding." Always preferable to Digital Sound in my opion. I've read that the SMSL Sandskri improves greatly in terms of "more punch in the bass, improved dynamics and cleaner sound overall" when using the external power source as opposed to USB via a computer. Makes sense.
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.