IM50 & IM70, dual dynamic driven ... IM01 single BA, IM02 dual BA and so on 

Generally, BA sounds smoother while dynamic sounds more musical 

It's all about implementation. Not all BAs are super expensive, and they can sound very good too even at a budget, like the SoundMagic PL50 at about RM200. Some single BAs are cheaper still, but you won't find any BA under RM150 I think. BAs are speakers that have small arms (hence the name "armature") that is moved by the magnetic assembly and attached to the diaphragm. The arm is balanced in between the magnetic assembly, hence the name "balanced armature". The arm can stick to one of the magnets if it's not centred properly within the assembly. The technology isn't new, in fact it's been around since the 50's. It was primarily designed for efficiency. They don't "move" the air to make sound, they just make it vibrate until it reaches your eardrum, so they don't need ports and a vacuum seal is easy (actually needed), and tuning the drivers for certain freq range is easy and they respond to it well. But because of the way they make the sounds, bass feel is virtually non-existent. However bass BA drivers have also been made but are quite expensive. So a multi-way with a bass BA is needed for a bass response you can feel. You can see why they can be very expensive.

Dynamics are rather straightforward. If you've seen a naked driver of a speaker, imagine that but miniaturized. Easier to build, and can be built easily to extend well beyond the frequency range of the human hearing (you can see dynamics having a response from 5Hz to 30,000Hz). They can also move a lot of air if need be. The trouble is they can be rather slow to react depending on the mechanical suspension, diaphragm mass, magnet strength, shell design, etc. They can sound good, but as you may know asking them to handle the full range of freq very well can be a problem, and a multi-way dynamic to split the job is difficult to do. But, it can be done and has been done (there's a 3-way dynamic now). Manufacturers can have fun with them too such as making a sort of mechanical crossover to achieve a multi-way setup, like different diaphragm coating or material for each driver, play around with port sizing, using the push-pull effect, whatever they fancy. In a way, the variety of a dynamic driver sound is vast.

Dynamic drivers do benefit from higher current from an amp.  However, that depends on your complete audio chain ( setup ) from type of files (.mp3, .flac, .dsf) > type of players ( or phones ) > DAC or amp or DAC/amp combo > earphones

Different ATH has different signature, in fact, the ATH woodies excel with female vocals 

Does your Sony comes with the dock connection or purely USB 

Walkman > FiiO L5 ( LOD ) > Amp > AT-HDC5 ( upgrade cables ) > ATH-M70

BAs are unstable electrically, relative to dynamics. Not all amps can power a BA well, but most decent ones can. Some reviewers reported that even a Graham Slee Voyager won't drive a BA well. I've paired a Hippo amp to a PL50 and it sounds horrible. I think everyone will notice it. I think it's because of the motor construction.

both the IM70 and CKR9 will do well without an amp 

If you are in KL, drop by Sungei Wang to compare them 

where to get the best bargain for audio technical?

Curious, does only the price matter to all of you instead of reputation, service and warranty