Hi guys,
I currently have my entire CD collection of 200+ discs ripped to MP3 using LAME with -alt-present-standard. I just recently picked up a 15 gig iPod, and I want to transfer my stuff over. I'm thinking about transfering them over at 160-bit CBR so I can fit more music on the iPod. I would do this by taking the current -a-p-s MP3 and re-encoding it before transfering it over, keeping the original -a-p-s. I'm only using the iPod with small headphones at the moment, usually at the gym, so sound quality isn't my highest priority. Just fitting the majority of my stuff.

I have a rather wide range of stuff: Electronica, Hip-Hop, Rock, Jazz, and Pop are the big ones.

So, I guess my two questions are this:

1 - Will I notice a decrease in sound quality by using an existing -alt-present-standard MP3 to create a 160 CBR MP3, versus using the original media to create a new 160 CBR MP3?

2 - Am I going to notice a difference between -a-p-s and 160 CBR on the iPod, taking into consideration the listening environment? Should I just scrape this plan, use the -a-p-s MP3s and better manage my collection?

Ideas, thoughts, appreciated. Many thanks ahead of time.

1 - Try using WinABX to determine how much of a difference you can hear. Lossy -> lossy transcoding (usually) inherently brings lower sound quality, but it's up to you how much of a drop is "acceptable". I used to transcode from LAME --api to LAME --alt-preset cbr 128 for my portables, and the difference in quality was somewhat noticable (via ABX) but acceptable to me when playing from my portable and listening through earbuds. Then again, I don't know how much of a drop I sustained by lossy-to-lossy transcoding vs. just using a lower bitrate, either.

2 - Same answer as #1.

Instead of 160k, try --alt-preset standard -Y. Encoding ultra high frequencies when not really needed is a waste on a portable, that'll lower the filesize.

MPC -xtreme to MP3 --alt-preset standard sounds bad to me, so I'd assume transcoding'd sound bad there too. Definately don't transcode.