Remove DRM from iTunes musics purchased before

"On Sunday, while perusing my music collection by album, I came across lots of new -- or rather, old and forgotten -- tracks purchased before Apple took iTunes DRM-free. My excitement at discovering, and downloading from the cloud, these long lost songs cannot be understated. That is until finding them not to be what I expected. Rather than crisp, 256kbps DRM-free files, iTunes delivered 128kbps protected-AAC tracks. What the frak? Apple is supposed be done with digital rights management for music.
That iTunes Match provides access to this older music, even if DRM-protected, is a benefit. Thank you, Apple, for providing an affordable means for recovering lost or deleted music. What confuses me: Being given the older, lower-quality, locked files when higher-bitrate DRM-free alternatives are available from Apple's store. I don't have an answer why this morning, but I do have some suspicions. Perhaps you're smarter than me or better at finding solutions in online support forums."
From Joe Wilcox - betanews.com

What can we do if we come across the same problem?

There may be lots of people having the same problem with Joe. We purchased music from iTunes music store before, but even Apple had given up the DRM protection on music, we still get our music DRM free. Is there any way we can resolve this issue?

The answer is "Yes". By searching the result on Google, we will get some DRM removal software recommended. We will recommend Aimersoft DRM Media Converter to remove iTunes DRM

Reviews About Aimersoft DRM Media Converter for Windows

Aimersoft DRM Media Converter is a professional DRM removal and media converter software for Windows users. It is designed to remove DRM from video and audio files downloaded from iTunes, BBC iPlayer, Windows Media Center, Amazon etc. The highlight of this software is that it supports tons of media formats as output and can fit various mobile devices.

Specifics of Aimersoft DRM Media Converter

Supported output video formats: ASF, MOV, M4V, MP4, WMV, MKV, AVI, Xvid, DV, MPEG-1, MPEG-2, VOB, TS, TRP, HD AVI, HD MP4, HD MPG, HD WMV, HD MOV, FLV, F4V, SWF.

Supported output Audio formats: MP3, M4A, AC3, AAC, WMA, WAV, OGG, APE, MKA, AU, AIFF, FLAC, M4R.

Supported output devices:iPhone (iPhone 5), iPad (iPad mini), iPod (iPod touch 5), Apple TV, HTC, Motorola, Nokia, LG, BlackBerry, Samsung (Samsung Galaxy III), Sony, Xbox 360, PSP, PS3, Wii, NDS, Zune, Archos, Creative Zen, iRiver and more.