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
Ran across this Modi 3 review (revisited) that was quite interesting.

(164) Schiit Modi 3 Revisited (2 months later) - YouTube 

In the second part of the review, he talks about the sound quality improvement that resulted from placing small weights on top of the Modi 3 case. I didn't have those particular weights on hand so instead I placed a book on top of the case and was taken back by the sound improvements. In particular, the upper midrange and highs were cleaner and more focused.

It makes for a no-cost experiment and you might be surprised (and pleased) by the result. No reason to think it wouldn't work for other light-weight DACs as well.
Now that's interesting turnbowm. I'll gives that a shot and post my thoughts!Thanks.
So I don't know about the weights although I agree that the unit should sit firm on the table, but it does appear to "break in" after about 50+ hours. Sounds less "brittle' and a bit fuller. I think maybe at some point I'll play with cables as they certainly effect overall output. For $100.00 with nothing other than my OPPO to compare, I'd say it's a decent deal.
I usually have my Modi 3 in a stack with the Vali 2 on top.  It's not a lot of weight, so I can't really say if it's been a help.  What I do know is that any dac I've got sound mediore when plugged into my avr.  They are sound much better with the Vali 2 and my Grados.

I think it's because the AVR has too many compromises to the audio quality, and perhaps the preamp circuitry was one of the compromises.  I run the AVR in direct mode, which apparently doesn't process the signal in any way.  It doesn't even extract anything to feed the subwoofer.  

The dacs also sound much better in the 2 channel rig with a proper pre.
Currently mu Modi3 is direct RCA connected to PrimaLuna Integrate. It's sounds okay but I'm wondering is a different Lap Top to Modi3 cable might help. using the stock cable. .