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 always liked Analysis Plus cables, not all that expensive but very good build quality. Signal Cable too.
I switched from a generic USB data cable to an AudioQuest ‘Cinnamon’ cable $80 and noticed a drastic improvement in sound quality. 
To be honest, I had a pair of MIT "Terminator" speaker cables which were good. but am now running AudioQuest spooled 14 AWG "Zip" cables and never been happier. I'm sure their USB cables are very good!
So Modi 3 arrived today. Attempted to hook up with old Windows 7 laptop. Would not install even though there was software for Win 7, Drivers included. I kept getting error message "Please Connect The Cemedia USB20 Device." ?? Tried Cemida drivers, etc, no dice!
After much trial & tribulation, and many attempts at installing various drivers, I finally got the "Gen 2" version of Modi 2 to install.So it plays but I've got to say; IT DON"T SOUND NO BETTER THAN BEFORE!
USB to Modi, RCAs to amp.
VERY Disappointed! Maybe with Gen 3 drivers would sound better but don't see how to install.Guess I'll sleep on it and see what's what over the week end.