And I quote..........
Amplifiers and Effects
Rory used various makes and models of amplifiers during his career. In general, however, he prefered smaller 'combo' amplifiers to the larger, more powerful 'stacks' Marshall Amplification that are popular with rock and hard rock guitarists. To make up for the relative lack of power on stage, he would often link several different combo amps together.
When Rory was with Taste, he used a single Vox AC30 with a Dallas Rangemaster treble booster plugged into the 'normal' input. Examples of this sound can be heard on the Taste albums, as well as the album Live in Europe. Brian May, of the band Queen, has admitted in interviews that as a young man, he was inspired to use a similar amplifier and treble booster setup after meeting Rory and asking him how he got his sound.
In the early to mid 70s, Rory began to use Fender amplifiers, most notably a Bassman and a Twin, both of a 50s vintage. An example of this sound can be heard on the Irish Tour '74 album. Rory also had a Fender Concert amp.
In the mid to late 70s, when Rory was moving towards a hard rock sound, he experimented with Ampeg VT40 and VT22 amps. He also began using Marshall combos. During this period and beyond, Rory used different combinations of amps on stage to achieve more power and to blend the tonal characteristics of different amps.