Hi All I would like your advice on my problem and my (lack of ) knowledge on this subject,

I have a setup of a Wireless Network drive ( Buffalo link station) to which I have "ripped" my CDs to the apple lossless format.  I then link it to my amp with a Roku soundbridge M1001 via a toslink optical digital connection. Amp is a Pioneer E08 THX certified AV amp and the speakers are Monitor Audio Silver S6. 

It is my understanding that CDs ripped to a lossless format to a hard disk are the same quality as the original CD.  Then the wireless connection transmits the same info to the soundbridge which transfers the same quality to the amp i.e. the same as the CD.  This is then converted to analogue via the amp's internal converters amplified and sent to the speakers.  So my percieved lack of quality may be due to the D/A conversion on the amp and the amplification of the amp or the quality of the speakers.   However before I spend my money I would like your advice.

i thought a seperate D/A might improve things or do I need a new amp or both (I hope not!) Hopefully the speakers are OK.  Help please!

What are you comparing it to? Is your CD player connected digitally to the amp or do you just use two analogue RCA cables? What is your CD player.

There are other things that can happen too. These wireless networks can exhibit more jitter than a CD player on it's own but it should be pretty similar sounding if one right.

I suspect that you prefer the DAC on your CD player to the one on your amp in which case you could purchase a new DAC without changing the amp.

There are a couple of things you could try first though. 1) You could wire the router to the Roku rather than going wireless to see if that helps - even if just as a short term experiment. 2) You could try using a standard RCA digital lead rather than a glass fibre one.
3) Try using the DAC in the Roku.