In my experience it doesn't matter who you use, assume they're gonna drop and/or crush the package. Package anything you send so that it will withstand being dropped - if you can feel through the packaging you haven't used enough.
Parcel2Go are good - they have a flat rate based on weight-brackets. They subcontract their work out to DHL but are alot cheaper than going directly through DHL.
I've always found Parcelforce to be fine but you're now constricted by the 20kg weight limit.
I've shipped amps to USA, Canada, Italy, France, Ireland - all over the place so shoot me some questions if you need to.
:twisted: