[jz9chen]

What do non coloring amps do aside from making things louder?
If nothing, then what's the difference between a cheap and expensive non color amps? 
 
Thanks =)

 

[KamijoIsMyHero]

Features (bass boost, crossfeeds, variable gain ... etc), mainly. Build quality, power, looks, form factor, specs.... lots more!

 

[SharpEars]

  What do non coloring amps do aside from making things louder?
If nothing, then what's the difference between a cheap and expensive non color amps? 
 
Thanks =)

 
Aside from amplifying the signal, they also add noise, crosstalk and inter-modulation distortion. On any good amplifier, these are measured and specified as part of the specs.
 
What separates an expensive transparent amplifier from a cheap one? Here are some items listed from most relevant to least relevant.
 

• Its power in watts RMS and the ability to drive small (i.e., low impedance loads), before the THD crosses a certain threshold.
• The noise characteristics mentioned in the first paragraph along with other attributes such as slew rate and dampening factor.
• The type of amplifier (i.e., class A, class A/B, class D, class H). The amplifier's efficiency is highly dependent on this.
• A balanced topology (vs. single-ended). The benefits of this are considered dubious in nature, unless there is a very long (interconnect) cable run to the amplifier from the pre-amplifier or source.
• Parts tolerance and reserve capacitance.
• Quality of construction, durability and a reasonable maintenance free life.
• Cosmetics including materials used for construction, weight and other physical attributes that have little to do with how the amplifier performs sonically.

 
I hope that answers your question to a reasonable extent.