When does it make sense to place preamp between components?

[DVDdoug]

The arcam sr250 has class a operation beneath some watts so there is much to like (exept for some class a leanness in the bass regions).

That shouldn't be happening. The class of the amplifier shouldn't affect frequency response.

The class is mostly related to electrical efficiency. Class-A was the 1st, most inefficient design and it could be built cheaper in the old days because you only need 1 tube or transistor in the output stage. Class A/B requires two output devices. These days when electronics are cheap, A/B is more economical. (And class-D is becoming the most economical if it's not already.)

ALL class A/B amplifiers are essentially operating class-A at low levels. That's what A/B means. (There are no class-B hi-fi amplifiers.)

Lots of hifi babble to conclude it already has a nice preamp build in but much work is to be done in the room acoustics department.

The audiophile community is dominated by nonsense! But Audio Science Review is rational and scientific. Audiophoolery defines the 4 TRUE characteristics of "sound quality".

I guess 0 db is a bit too loud.

Decibels have to be relative to something... 0dB of gain, or a 0dB change means no change, or a gain/attenuation factor of 1.0.

Or you need a reference - Acoustic sound levels are measured in dB SPL where 0dB SPL is approximately the quietest sound that can be hard by humans and SPL levels are positive. The digital reference is 0dBFS (decibels full scale) which is the digital maximum* so digital dB levels are normally negative. There are also various dB references for electrical signals.

There is no fixed calibration between digital and acoustic levels (except movie theaters are calibrated). But there is a direct correlation and if you reduce the digital level by 3dB (a larger negative number) the SPL also drops by 3dB, etc. (That's assuming everything is linear and you're not over-driving your amplifier into distortion, etc.)




* With regular integer audio (16 or 24 bits, etc.) 0dBFS is represented by the highest positive or negative value you can "count to" with a given number of bits. CDs. regular WAV files and DACs are all hard-limited to 0dB. With floating point data, a value of 1.0 represents 0dB. With floating point you can go over 0dB and there are virtually no upper or lower limits. When you play the file, everything is automatically scaled to match the bit-depth of your DAC so although the numbers in a 24-bit file are bigger than those in an 8-bit file, the 24-bit file isn't "louder".

 

[Chrispy]

It's a bit embarassing I did set the subwoofer volume much too high. It sounds much less 'liveless' and more open now. I guess 0 db is a bit too loud.

How are you level matching sub to speakers?