This, my first post here at head-fi, is intended primarily for on-a-budget music listeners like me, who likes and/or needs to squeeze the juice of the pennies.
I write this post to share a very specific experience that could be of help to someone. I'm not saying that the headphones and/or soundcard that I will mention below are good/better than others since I'm not able to make such comparisons. I want you to know that although I really enjoy to hear music through my headphones I barely have any knowledge in the audiophile field.
I bought the Samson SR-850 headphones (Superlux HD-668b) a year ago after reading opinions about it here at head-fi. I've found mixed opinions before buying them, but most of them were favorable and described very well indeed what I wanted from a pair of headphones: detail, separation and a not-boomy sound. I cannot compare its performance to other headphones but I think that these are the characteristics of the SR-850. Last but not least, I chose this headphones based on their price (I live in Argentina and the electronics and imported goods are comparatively more expensive than in the US or Europe for example). Some posters at head-fi and other websites complains about the harshness/crispiness of their sound in the higher frequencies section. Of course, I have noticed this and must say that, without an equalization of the trebles, some albums were very hard to listen to. Anyway, I think that the overall performance of the headphones compensates this issue largely.
The headphones worked very well when plugged to my vintage Technics amplifier or to the Sansa Clip Zip, but when used with my laptop's headphone jack the trebles "flaw" seemed to worse a lot, while adding a low but disturbing hum and fry noise, especially in quiet tracks like piano music for example. This situation was annoying since I mostly hear to music through the laptop. I was thinking about buying another pair of headphones that could complement the Samsons in order to use them with the more treble exagerated albums. And I'm very glad that instead of doing that, I tried with an external soundcard to bypass the laptop's jack.
I bought the relatively cheap Encore ENMAB-8CM external sound card and the improvement is undeniable. The subtle hum/frying noise disappeared and the sound turned more "fuller" than before, specially towards the low side of the spectrum, without adding any new unwanted noise or distortion. The Samsons are labeled 32ohms and because of that it's supposed that they should not require an amplifier. But I think that the right question is if they need or not a stronger source *compared to what*. The Sansa Clip Zip drives the headphones better than the laptop's jack and the Encore's output seems to do it better than the formers. The Encore sound card gives a louder output to the headphones and this have positive effects on the lower frequencies, making a better balance in relation to the higher frequencies and fixing noticeably the harshness issue. I don't know if this conclusion is technically right, it's only my subjective impression of the change from the laptop's output to the external sound card.
Based on my own experience, the adquisition of this sound card resulted in a very good improvement and gave a new value to my already owned headphones. Taking into account the fact that its price is about of only 20 dollars, I don't hesitate to recommend it others in a similar situation (improvement on a low budget). The sound-card's case although made of plastic appears to be very durable and the output jacks seems solid to bear daily use. The sound card has 7.1 output but I don't know how it works since I used it only through the headphones output.