Sennheiser HD 598 vs Beyerdynamic DT 990 PRO Side-by-Side Headphones Comparison - RTINGS.com
Beyerdynamic DT 990 PRO vs Sennheiser HD 560S Side-by-Side Headphones Comparison - RTINGS.com
Amazon.com: Mchoi Hard Portable Case Compatible with M-Audio HDH40 Over Ear Headphones/Beyerdynamic 459038 DT 990 PRO/DT 770 PRO Open Studio Headphone, Case Only : Electronics