Need advice on built-in rack

My basement listening room is 'roughed-in' and includes a 23" x 21" alcove for equipment. Will have a cabinet door in the rear for easy cable access. Also have a 25' run of 2" rigid PVC for pulling I/C's or speaker cable to the speakers so I can still experiment with cable. Will make provisions for ventilation.

My thoughts are either a) lag bolt angle iron into the alcove studs to support maple butcher block shelves; maybe even drill and tap the angle iron and use spiked set screws to support the shelves. Or;

b) Buy/build a free standing rack inside the alcove coupled to the concrete floor. Trim out to look built-in.

I seek opinions and advice. High priority on audio sound but want a clean look. Can always use the alcove to shelve LP's if a built-in rack is a bad idea.

70% audio/30% HT, Existing/Planned equipment:
Merlin VSM's
Berning ZH-270
Cat SL-1 mk 3 pre
Anthem processor
Pioneer Blu-ray
Linn Ikemi CDP
Linn LP-12 (not in rack)
Sony XBR2 52" LCD
rear amp/speakers tbd
i built one with dry sand bags and unscented cat liter, i know , you are saying, this guy is ,well, i used maple butcher block for shelving and it is dead silent with all areas being monitored for and decrease in low,mid,high freq. none...then built the are welcome..dwhitt a real audio nut....thirty pound bags of sand, make sure it is dry sand.