Would someone explain what "up sampling" means and how it can affect the sound?

Oversampling - integer multiple of original rate
Upsampling - non-integer multiple of original rate

For instance, my Benchmark DAC1 is upsampling (and not the oversampling) DAC,

Specifications relating to how devices interface with other devices are always important. Many examples some of more consequence than others, but you ALWAYS want to know if or how well one device will work with another before buying.

Other specs or aspects of design are of interest also of course but harder to "bank on" in that there are so many factors that go into a quality design and product and what people judge as "good sound" that you never really know for sure what's good for you until you hear for yourself

tls49 and chayro - ordinarily I would ignore such a foolish and technically inaccurate response (from the both of you), however, I have ample time and desire to stir things up a bit to reiterate how wrong you are. Nowhere have I stated that someone should not listen with their own ears. What I have stated is that doing so is simply one more variable - albeit an important one - to the overall decision making process. The both of you, on the other hand, have gone as far as to completely discount everything except listening. And that is ridiculous, among many other other adjectives. 

I completely agree with Gdhal that all available information should be considered. For example, as Mapman alluded to and as I have stated in a number of past threads, specifications can often be particularly useful in **ruling out** components from consideration that would be poor matches to the components they would be used with. Thereby reducing the randomness of the component selection process, and the likelihood of expensive mistakes.

Also, "trust your ears" only goes so far. For example, obviously it is often not possible to audition a component in one’s own room with one’s own equipment. And just as obviously listening to a component in a less familiar environment with less than familiar associated equipment, probably during a relatively brief audition, will not necessarily say very much about how that equipment will sound to that listener in his or her own room with his or her own associated equipment, over the long-term.

Of course, this assumes that one has sufficient knowledge about specs to not misapply them. For example, if everything else is equal I would expect an amplifier having 0.0001% total harmonic distortion to be very likely to sound worse than one having 1% total harmonic distortion, when used in conjunction with many or most speakers. Why? Because the 0.0001% amplifier was probably designed with specmanship rather than sonics as the leading priority, and the 0.0001% THD figure was probably accomplished via heavy-handed application of feedback, with the adverse side effects that often go with it.

On another note, kudos to Bombaywalla for his excellent post.

Regards,
-- Al

Thank you, Almarg. :-)