Originally BT was not designed with high quality music in mind because there were no high quality devices then. It was mainly for a wireless replacement of phone to PC cables.
BT uses something called SBC codec to transmit audio. But this is compressed, like how MP3 is compressed audio. CD quality music is large which is about 10 MB +/- per minute of stereo. That is why MP3 was designed to reduce the file size - which is known as "Audio Compression".
There are different levels of SBC. If your device, say a hands free BT ear phone has the same level of SBC as your laptop / phone/ tab does, then they transmit equally at that rate. If any of your BT device has a lower SBC then device will transmit / accept at the lower speed of the two.
To improve this, A2DP was designed for stereo audio. Think of it as a kind of layer which is on your BT. A2DP allows you to stream your audio over any codec, but it requires the SBC codec as a minimum to make sure that all A2DP devices work when they are paired.
If you are specifically looking for transmitting stereo audio over BT then you need APTX. It is generally advertised as the best quality codec for CD like quality and found on most latest A2DP devices. If you have APTX support on both - your laptop in this case and a pair of APTX head phones then you will get your audio over APTX instead of SBC.
But this APTX is still compressed but just better compression. For me it still does not make sense to get APTX enabled hardware and devices like speakers / headphones and not being sure whether they are paired with purely APTX. Your BT compression is in addition to the compression of your music. So if you play MP3, it gets decoded then again compressed with BT. That for me is not the way to good sound. So whatever the devices have, both should have the same level / version of that codec to transmit / receive equally.
Coming to your point @balajeem Since you mentioned laptop, I am assuming you have your music stored in it and probably a HDD connected to it. You have not mentioned whether you are using a DAC with your amp and the type of music (MP3 / FLAC / AAC / etc.,) you have. Since you have a Rotel amp (a damn good one), you need a BT setup which has RCA / digital output, from which you can connect to amp. Typically you will have a small box with analog / digital out with which you can connect your amp and playback music via your laptops BT. You do not need any additional software for that.
I have a lot of FLAC files and have used, returned and donated many BT audio receivers because I found a slight loss of sound quality. Mind you it is not bad at all especially if you or your family members want to play MP3 from their phones; but for a good ear it is not acceptable. The best one which
I came across is
Bluetooth Receiver with optical out and NFC, but I gave it to my nephew after a few days and switched back to hard wire. This has an inbuilt Wolfson DAC and would be ideal for those who do not have an external DAC. I had got it for 6.5K on Amazon last year.
Now, I am playing back from my laptop to DAC to amp - all wired. You do need a good software like JRiver / Foobar / VLC to playback FLAC files though.
If you are fixated on playing back wirelessly, then go in for a wifi enabled one like
Wireless Receivers Wi-Fi. Both the products in the links are for illustrative purposes only.
On the Forum, there is a wealth of much better information than what I have tried to say. Bottom line: Stay wired.
it's awesome !
