The Phaze II bar opened in December 1991 in downtown Madison, just a block off of Capitol Square, in the space previously known as The Shamrock bar, and owned by the same man, J.J. O'Connell. Unlike the more laid-back Shamrock, Phaze II intended to be a popular dance bar.

The bar ran ads that supposedly celebrated their 8th anniversary in 1993, but the advertisement for that event included the words "Shamrock Inc." in the logo-- subtly reminding patrons that the bar had originally opened as The Shamrock bar. So the 8th anniversary actually included its years as The Shamrock. In fact the name "Phaze II" only lasted from December 1991 to September 1994, when they reverted back to the "Shamrock" name.

Three other bars nearby had tried to compete with The Shamrock/ Phaze II. A few doors away at 121 W. Main St., Kirby's Klub was open from 1998-99; Scandals from about 1999-2000 (named because the previous club was abruptly changed because of rumors of someone running off with all its cash assets); and the Rainbow Room from 2000-04.

The Shamrock bar (briefly Phaze II) survived for over 35 years at their location, far outliving all of these bars, and still operating in 2023.