Low volume on albums; should I amplify?

[Prodo123]

I have ripped a lot of my collection to FLAC/ALAC (lossless, 16 bit and 44.1Khz) but I've noticed that some of my albums (like Tool's Lateralus) is a bit soft. I've set out to tweak the rips a bit.

On Audacity I can amplify a good amount without clipping. However, as rudimentary as Audacity is, I'm fearing a loss of audio quality and artifacts being left behind by the amplification process.

Should the file be fine after the amplification?

 

[Prodo123]

What worries me is the varying amount of amplification necessary for each file; one song needs 12.4dB while some need 6dB. Consecutive, transitioning tracks seem to end up with the same overall volume though, which confused me...

Update: After amplification, the bitrate (which used to be around 1500Kbps average) has roughly halved on all the files.
And they sound a lot more comfortable.
No artifacts or distortion yet. Although I'll have to do more careful listening to tell
The album in question was Tool's Lateralus.

 

[Destroysall]

Just turn up the volume knob. I wouldn't do it any other way.

 

[TwoBytes]

No. It was mastered that way for you to listen and enjoy without clipping things. Things like this are the crux of the loudness war. Reach for the volume knob!

 

[Prodo123]

No. It was mastered that way for you to listen and enjoy without clipping things. Things like this are the crux of the loudness war. Reach for the volume knob!

It was mastered using the HDCD process which might have caused some issues and this is by no means related to compression.
I am not compressing music nor amplifying a compressed album. The volume ceiling was set to 0.5 and I am simply reexpanding it to 1.
It's very strange that a 16 bit/44.1Khz file had a 1510Kbps bitrate when the maximum bitrate is supposed to be 1411Kbps. The amplification resolved this issue without introducing clipping.